Psalms 85:8

I will hear what God the Lord will speak
This the psalmist says in the name of the people of the Jews, whom he represents, in all the foregoing expostulations and petitions, refusing to be still and quiet, and wait and listen for an answer to the above request from the Lord, who speaks by his providences, word, and Spirit; see ( Habakkuk 2:1 ) ,

for he will speak peace unto his people, and to his saints;
as he does in his word, which is the Gospel of peace; and by his ministers, who bring the good tidings of it, and publish it; and by the blood and righteousness of his Son, which both procure, call for, and produce it; and by his Spirit, the fruit of which is peace: it is an answer of peace, or of good and comfortable words, that the Lord returns to his people sooner or later; and it is only to his own people he speaks peace, to his covenant ones, with whom the covenant of peace is made; and to his saints, his Holy Ones, whom he has set apart for himself, and sanctified by his Spirit: as for the wicked, there is no peace unto them, nor any spoken to them by him: Kimchi understands by the "saints" the godly among the Gentiles, as distinct from the Lord's "people", the Jews:

but let them not turn again to folly;
to doubt of and question the providence of God; so Arama; or to idolatry, which there was danger of, upon the Jews' return from Babylon; and it is observable, that they afterwards never did return to it, to which they were so much addicted before; or to a vicious course of life, to sin and iniquity, which is the greatest folly, after mercy has been shown; or to self-righteousness, and a dependence on it, to the neglect of Christ and his righteousness, which is the great folly of the Jews to this day; and when the Lord shall quicken them, and convert them, show them his mercy and salvation, speak peace and pardon to them, it would be very ungrateful in them to turn again to this folly.