You had asked:
Please interpret this verse for me and who are these people which named here His people ?
Ps.73:10 :-Because of this His people shall return here; and waters of a full cup shall be drained by them. 11:-And they say, How does God know? And, Is there knowledge in the Most High?
I think "His people" refers to ethnic (corporate) Israel, and not true spiritual Israel (i.e., the elect of God). I will expound on this further below:
"Truly God is good to Israel, to those who are of a pure heart. And as for me, my feet had almost stumbled, my steps nearly made to slip. For I was jealous of the proud; I looked upon the peace of the wicked. For there are no pangs to their death; but their body is fat. They are not in the misery of mortal man; and with men they are not touched. So pride enchains them; violence covers them like a robe. Their eyes go out with fatness; they have passed the imaginations of the heart. They scoff and speak in evil; from on high they speak oppression. They set their mouth in the heavens; and their tongues walk through the earth" (Psalm 73:1-9).
The Psalmist says that God is good to Israel, to those who are pure of heart. Not all within Israel are pure in heart. Of course, "pure in heart" does not mean sinless in heart, but it does mean that there is a striking contrast between the ungodly and the pure in heart within Israel. Commenting on Psalm 73:9, Calvin writes:
"Here it is declared that they utter their contumelious speeches as well against God as against men; for they imagine that nothing is too arduous for them to attempt, and flatter themselves that heaven and earth are subject to them. If any should endeavor to alarm them by setting before them the power of God, they audaciously break through this barrier; and, with respect to men, they have no idea of any difficulty arising from such a quarter. Thus, there is no obstacle to repress their proud and vaunting speeches, but their tongue walketh through the whole earth" (John Calvin commentary).
I think that given the context of verses 1-9, those who "scoff and speak evil" and "set their mouth in the heavens" are the pagans who are outside of the ethnic (corporate) people Israel. IF the correct interpretation is that verse 9 refers to pagans alone, then we see from verses 10-19 that ethnic (corporate) Israel are nevertheless lumped in the same category–namely, "ungodly."
Thus, it appears that by witnessing the seemingly "prosperous" lives of the wicked despite their proud and audacious speeches against the providence of God, many who profess faithful adherence to the God of Israel are made to stumble and end up joining hands with the pagan idolaters in their prideful rebellion against the Most High. A modern-day instance: Many Calvinists would never "join hands" with the atheists by saying they agree with their contumelious (contemptuous) speeches against God's providence (e.g., so-called problem of sin/evil). But these Calvinists exhibit much greater deceit than the atheists by cloaking and clouding their audacious "speeches" (e.g., answers, sermons, writings, etc.) in "mystery." Note the vain attempt of Machen to hide his mutiny against God under the deceptive cloak of "reverence and humility":
"Why He allowed sin to enter is the mystery of mysteries, but that He did so we are plainly told, and that He did so for some high and holy end" (J. Gresham Machen, The Christian view of man, p. 101).
Responses like Machen's are common among the Calvinist Reformed. When things like God's wisdom, love, justice, and righteousness are called into question by irreligous pagans, ungodly Calvinists like Machen concede their arguments by giving a dishonest answer. The atheist is right out in the open in his rebellion while certain Calvinists more subtley rebell by appealing to "mystery" and "insolubility":
"How could a holy God, if He is all-powerful, have permitted the existence of sin? What shall we do with the problem? I am afraid we shall have to do with it something that is not very pleasing to our pride; I am afraid we shall just have to say that it is insoluble" (J. Gresham Machen, The Christian view of man, p. 45).
Obviously, it is Machen who is pleasing his wicked pride and rebellion against the Most High by refusing to acknowledge what God has clearly revealed in Scripture concerning the demonstration of His power, wrath, justice, holiness, grace, love, and mercy in actively causing the entrance of sin into the world. Not only are the irreligious pagans setting their mouth against the heavens (Psalm 73:9), but so are those of J. Gresham Machen's mind. God has plainly revealed WHY He caused sin to enter. Machen calls God a liar by asserting that God has not revealed this "WHY" and therefore it is a "mystery of mysteries."
"Because of this His people shall return here; and waters of a full [cup shall be] drained by them. And they say, How does God know? And, Is there knowledge in the Most High? Behold! These are the ungodly who are always at ease; they increase their riches" (Psalm 73:10-12).
As seen above, it appears that "His people" refers to corporate Israel. But what of the phrase: "…shall return here"? Return where? Because, or on account of what has previously been stated in verses 1-9, His people "shall return here." Matthew Poole comments:
"Return hither, or, turn hither, i.e. to this wicked company, or to their course" (Poole's commentary on the whole Bible).
The phrase "cup shall be" is either italicized or bracketed, signifying that it is not found in the original language. I believe that "they" who say "How does God know?" and "Is there knowledge in the Most High" further confirms that "His people" are those Israel according to the flesh, not those Israel according to the promise (cf Romans 9:1-8). Calvin agrees in the main, but still leaves room for the presumptuous interpretation that true believers may emulate the ungodly (verse 12) who posed the two questions in verse 11:
"Some read the whole verse connectedly, thus: The people of God return hither, that they may drain full cups of the water of sorrow. But, in my opinion, this verse depends upon the preceding statements, and the sense is, That many who had been regarded as belonging to the people of God were carried away by this temptation, and were even shipwrecked and swallowed up by it.The prophet does not seem to speak here of the chosen people of God, but only to point to hypocrites and counterfeit Israelites who occupy a place in the Church. He declares that such persons are overwhelmed in destruction, because, being foolishly led away to envy the wicked, and to desire to follow them, they bid adieu to God and to all religion. Still, however, this might, without any impropriety, be referred to the chosen seed, many of whom are so violently harassed by this temptation, that they turn aside into crooked by-paths: not that they devote themselves to wickedness, but because they do not firmly persevere in the right path. The sense then will be, that not only the herd of the profane, but even true believers, who have determined to serve God, are tempted with this unlawful and perverse envy and emulation" (John Calvin commentary).
In contrast to Calvin's admission of a possible interpretation of the passage referring to the chosen seed, Poole states:
"Those wicked ones, whose words and actions he hath been hitherto describing, or the people confederate with them. For these and such-like opinions are oft ascribed to the wicked in Scripture, but never, as far as I know; to any good man. And Job, though he used many intemperate speeches, and though some such expressions as this were charged upon him by his friends, as Job 23:13, yet he utterly disowned them. Is there knowledge in the Most High? seeing these cursed and impudent blasphemers of God, and enemies of all goodness, are crowned with so many blessings, how is it credible that there is a God who sees and orders the affairs of this lower world? for if God did know these things, certainly he neither could nor would suffer them to be thus managed" (Poole's commentary on the whole Bible).
As for these "waters" being "drained by them" I'm not sure. But I thought of this passage in light of it:
"And I do not want you to be ignorant, brothers, that our fathers were all under the cloud, and all passed through the Sea. And all were baptized to Moses in the cloud, and in the Sea, and all ate the same spiritual food. And all drank the same spiritual drink; for they drank of the spiritual rock following, and that Rock was Christ. Yet God was not pleased with most of them, 'for they were scattered in the deserted place.' But these things became examples for us, so that we may not be lusters after evil, even as those indeed lusted. Neither be idolaters, even as some of them, as it has been written, 'The people sat down to eat and drink, and stood up to play.' Nor should we commit fornication, as some of them fornicated, and twenty three thousand fell in one day. Neither test Christ, as some of them tried Him, and perished by serpents. Neither should you murmur, as also some of them murmured, and perished by the destroyer. And all these things happened to those as examples, and it was written for our warning, on whom the ends of the ages have come" (1 Corinthians 10:1-11).
ALL Israel ate the same spiritual food and drank the same spiritual drink but only SOME Israel were among the remnant, "the children of the promise" (Romans 9:8). The wicked within Israel experienced things like water and food, but unlike the righteous within Israel, these wicked despised God's provision:
"He split the rocks in the wilderness and made them drink, as from great floods. And He brought streams out of the rock, and caused waters to go down like rivers. Yet they sinned still more against Him, to provoke the Most High in the desert. And they tested God in their heart, by asking food for their souls. And they spoke against God, saying, Shall God be able to set a table in the wilderness? Behold! He struck the rock and the waters gushed out, and the torrents were overflowing. Can He also give bread? Will He provide flesh for His people? So Jehovah heard and He passed over, and a fire was kindled against Jacob, and also anger went up against Israel, because they did not believe in God and trusted not in His salvation. And He commanded the fine clouds above; and He opened the doors of the heavens; and He rained on them manna to eat; yea, He gave the grain of the heavens to them. Man ate the bread of the mighty; He sent them food to the full. He made an east wind blow in the heavens; and He led out the south wind by His power. Yea, He rained flesh on them like dust, and winged birds as the sand of the seas. And He made them fall amidst their camp, all around to their tents. They ate and were filled full; for their own lust He brought to them. They were not estranged from their lust; their food was still in their mouths, and God's wrath came on them and killed the fattest of them; and He struck down the choice ones of Israel" (Psalm 78:15-31).
God gives them water and they say can He provide bread? God provides bread (i.e., manna) and they say can He provide flesh? He provides flesh and strikes them dead in His wrath while the flesh was yet between their teeth:
"And the mixed multitude among them lusted with a great lust; and the sons of Israel also turned back and wept, and said, Who shall cause us to eat flesh? We remember the fish that we ate in Egypt for nothing; the cucumbers, and the melons, and the leeks, and the onions, and the garlic; and now our soul withers. There is nothing except this manna before our eyes. And the manna was like coriander seed, and its appearance like the appearance of bdellium resin gum. And the people went around and gathered it, and ground it in mills, or beat it in mortars, and boiled it in a pan, and made it into cakes. And its taste was like the taste of fresh oil. And when the dew came down on the camp by night, the manna came down on it. And Moses heard the people weeping by its families, each at the door of his tent; and the anger of Jehovah glowed exceedingly, and in the eyes of Moses it was evil…And a wind went forth from Jehovah and cut off quails from the sea, and let them fall by the camp, as a day's journey here, and as a day's journey there, all around the camp, and about two cubits above the face of the land. And the people rose up all that day, and all that night, and the day after, and gathered the quails; he who had least had gathered ten homers. And they spread them out for themselves around the camp. The flesh was yet between their teeth, it was not yet cut off, and the anger of Jehovah glowed among the people. And Jehovah struck among the people with a very great plague. And one called the name of that place, The Graves of Lust; for there they buried the people who lusted. From the Graves of Lust the people pulled up stakes to go to Hazeroth, and they remained in Hazeroth" (Numbers 11:4-10, 31-35).
In short, I think that "His people" are those who profess to believe in the true God of Israel but who later make shipwreck of this profession by observing the seeming "blessings" upon the rebellious wicked and so begin to reveal their discontent and contempt of His provision. Those wicked Israelites who exposed their rebellious attitude in Psalm 73:11 are equated with the other wicked persons in Psalm 73:9. The spiritual Israelites on the other hand do not stumble and realize that the "prosperous wicked" are being deliberately set in slippery places that they may be cast down to destruction (Psalm 73:18). Also, the aforecited Scripture passages (from Numbers 11, Psalm 78, and 1 Corinthians 10) are a good commentary or exposition on Psalm 73:1-12.
Now when we apply all of this to our modern-day situation, we see how many Calvinists who profess to have faith in the true God end up giving essential agreement in their theology with the irrelgious pagans. So, it is not only the atheists, agnostics, and Arminians who are "speaking against the heavens" (Psalm 73:9), it is also the Calvinists. All of them are heading the charge against the Lord and against His Anointed (Psalm 2:1-3) by their shameful mutiny. Machen is a case in point among these contumacious Calvinists. Machen's views embody and epitomize the views of most who are in the camp of conservative Calvinism, so to expose him is to expose all those who believe like him.