Adams on Psalm 50:15, 18, 21

15 Call upon me in the day of trouble, etc The Lord hath promised his children supply of all good things, yet they must use the means of impetration; by prayer. He feed the young ravens when they call upon him. Ps 147:9. He feeds the young ravens, but first they call upon him. God withholds from them that ask not, lest he should give to them that desire not (Augustine). David was confident that by God's power he should spring over a wall; yet not without putting his own strength and agility to it. Those things we pray for, we must work for (Augustine). The carter in Isidore, when his cart was overthrown, would needs have his god Hercules come down from heaven, to help him up with it; but whilst he forbore to set his own shoulder to it, his cart lay still. Abraham was as rich as any of our aldermen, David as valiant as any of our gentlemen, Solomon as wise as any of our deepest naturians, Susanna as fair as any of our painted pieces. Yet none of them thought that their riches, valour, policy, beauty or excellent parts could save them; but they stirred the sparks of grace and bestirred themselves in pious work. And this is our means, if our meaning be to be saved.

18 Thou consentedst with him To give entertainment to them we know to be dissolute, is to communicate with their sins.

21 These things hast thou done, and I kept silence Neither sleep nor slumber, nor connivance, nor neglect of anything can be incident to God. Because he doth not execute present judgment and visible destruction upon sinners, therefore blasphemy presumptuously infers - will God trouble himself about such petty matters? So they imagined of their imaginary Jupiter. Non vacat exiguis rebus adesse Jovem. What a narrow and finite apprehension this is of God! He that causes and produces every action - shall he not be present at every action? What can we do without him, that cannot move but in him? He that taketh notice of sparrows and numbers the seeds which the very ploughman thrusts in the ground, can any action of man escape his knowledge, or slip from his contemplation? He may seem to wink at things but never shuts his eyes. He doth not always manifest a reprehensive knowledge, yet he always retains an apprehensive knowledge. Though David smote not Shimei cursing, yet he heard Shimei cursing. As judges often determine to hear, but do not hear to determine; so though God does not see to like, yet he likes to see.

As quoted in Spurgeon's Treaury of David.