C.H. Spurgeons's The Treasury of David
Verse 2. Let Israel now say, that his mercy endureth for ever. God had made a covenant with their forefathers, a covenant of mercy and love, and to that covenant he was faithful evermore. Israel sinned in Egypt, provoked the Lord in the wilderness, went astray again and again under the judges, and transgressed at all times; and yet the Lord continued to regard them as his people, to favour them with his oracles, and to forgive their sins. He speedily ceased from the chastisements which they so richly deserved, because he had a favour towards them. He put his rod away the moment they repented, because his heart was full of compassion. "His mercy endureth for ever" was Israel's national hymn, which, as a people, they had been called upon to sing upon many former occasions; and now their leader, who had at last gained the place for which Jehovah had destined him, calls upon the whole nation to join with him in extolling, in this particular instance of the divine goodness, the eternal mercy of the Lord. David's success was mercy to Israel, as well as mercy to himself. If Israel does not sing, who will? If Israel does not sing of mercy, who can? If Israel does not sing when the Son of David ascends the throne, the very stones will cry out.
EXPLANATORY NOTES AND QUAINT SAYINGS
Verse 2. Let Israel now say. Albeit all the elect have interest in God's praise for mercies purchased by Christ unto them, yet the elect of Israel have the first room in the song; for Christ is first promised to them, and came of them according to the flesh, and will be most marvellous about them. David Dickson.
Verse 2. Let Israel now say, that his mercy endureth for ever. Let such who have had an experience of it, acknowledge and declare it to others; not only believe it with their hearts, and privately give thanks for it, but with the mouth make confession of it to the glory of divine grace. John Gill.
Verse 2-4. Now. Beware of delaying. Delays be dangerous, our hearts will cool, and our affections will fall down. It is good then to be doing while it is called today, while it is called now. Now, now, now, saith David; there be three nows, and all to teach us that for aught we know, it is now or never, today or not at all; we must praise God while the heart is hot, else our iron will cool. Satan hath little hope to prevail unless he can persuade us to omit our duties when the clock strikes, and therefore his skill is to urge us to put it off till another time as fitter or better. Do it anon, next hour, next day, next week (saith he); and why not next year? Hereafter (saith he) it will be as well as now. This he saith indeed, but his meaning (by hereafter) is never: and he that is not fit today, hath no promise but he shall be more unapt tomorrow. We have neither God nor our own hearts at command; and when we have lost the opportunity, God to correct us perhaps will not give us affections. The cock within shall not crow to awaken us, the sun shall not shine, and then we are in danger to give over quite; and if we come once to a total omission of one duty, why not of another, and of another, and so of all? and then farewell to us. Richard Capel (1586-1656) in "Tentations, their Nature, Danger, Cure."