I will hear what God the Lord will speak - I, the psalmist; I, representing the people as looking to God. The state of mind here is that of patient listening; of a willingness to hear God, whatever God should say; of confidence in him that what he would say would be favorable to his people - would be words of mercy and of peace. Whatever God should command, the speaker was willing to yield to it; whatever God should say, he would believe; whatever God should enjoin, he would do; whatever God should ask him to surrender, he would resign. There was no other resource but God, and there was entire confidence in him that whatever he should say, require, or do, would be right.
For he will speak peace unto his people - Whatever he shall say will tend to their peace, their blessedness, their prosperity. He loves his people, and there may be a confident assurance that all he will say will tend to promote their welfare.
And to his saints - His holy ones; his people.
But let them not turn again to folly - The Septuagint and the Vulgate render this, “To his saints and to those who turn the heart unto him.” Our common version, however, has expressed the sense of the Hebrew; and it contains very important truths and admonitions.
(a) The way which they had formerly pursued was folly. It was not mere sin, but there was in it the element of foolishness as well as wickedness. All sin may be contemplated in this twofold aspect: as wickedness, and as foolishness. Compare Psalms 14:1; Psalms 73:3.
(b) There was great danger that they would turn again to their former course; that they would forget alike the punishment which had come upon them; their own resolutions; and their promises made to God. Compare Psalms 78:10-11, Psalms 78:17-18, Psalms 78:31-32. Nothing is more common than for a people who have been afflicted with heavy judgments to forget all that they promised to do if those judgments should be withdrawn; or for an individual who has been raised up from a bed of sickness - from the borders of the grave - to forget the solemn resolutions which he formed on what seemed to be a dying bed - perhaps becoming more thoughtless and wicked than he was before, as if to make reprisals for the wrong done him by his Maker, or as if to recover the time that was lost by sickness.
(c) This passage, therefore, is a solemn admonition to all who have been afflicted, and who have been restored, that they return not to their former course of life. To this they should feel themselves exhorted
(1) by their obligations to their benefactor;
(2) by the remembrance of their own solemn vows made in a time of sincerity and honesty, and when they saw things as they really are; and
(3) by the assurance that if they do return to their sin and folly, heavier judgments will come upon them; that the patience of God will be exhausted; and that he will bear with them no longer.
Compare John 5:14, “Sin no more, lest a worse thing come unto thee.”