Charles H. Spurgeon on Psalms 30:5

The princely prophet says plainly, heaviness may endure for a night, but joy cometh in the morning. As the two angels that came to Lot lodged with him for a night, and when they had dispatched their errand, went away in the morning; so afflictions, which are the angels or the messengers of God. God sendeth afflictions to do an errand unto us; to tell us we forget God, we forget ourselves, we are too proud, too self conceited, and such like; and when they have said as they were bid, then presently they are gone. Thomas Playfere.

Verses 5-10. When a man's heart is set upon the creatures, there being thorns in them all, therefore if he will grasp too much of them, or too hard, he shall find it. God's children are trained up so to it, that God will not let them go away with a sin; if they be too adulterously affected, they shall find a cross in such a thing. You may observe this in the thirtieth Psalm; there you may see the circle God goes in with his children. David has many afflictions, as appeareth by the fifth verse: I cried, and then God returned to me, and joy came. What did David then? "I said, I shall never be moved:" his heart grew wanton, but God would not let him go away so: "God turned away his face and I was troubled." At the seventh verse he is, you see, in trouble again: well, David cries again, at the eighth and tenth verses, and then God turned his mourning into joy again. And this is to be his dealing you shall find in all the Scriptures; but because we find his dealing set so close together in this Psalm, therefore I name it. John Preston, D.D. (1587-1628), in "The Golden Scepter held forth to the Humble."