Charles H. Spurgeon on Psalms 78:31

Slew the fattest of them. They were fed as sheep for the slaughter. The butcher takes the fattest first. We may suppose there were some pious and contented Israelites that did eat moderately of the quails, and were never the worse; for it was not the meat that poisoned them, but their own lust, Let epicures and sensualists here read their doom; they who make "a god of their belly, their end is destruction, "Php 3:19. Matthew Henry.

Verses 31-34. The Christian has more true pleasure from the creature than the wicked, as it comes more refined to him than to the other. The unholy wretch sucks dregs and all, dregs of sin and dregs of wrath, whereas the Christian's cup is not thus spiced. First, dregs of sin; the more he hath of the creature's delights given him, the more he sins with them. Oh, it is sad to think what work they make in his naughty heart! they are but fuel for his lust to kindle upon; away they run with their enjoyments, as the prodigal with his bags, or like hogs in shaking time; no sight is to be had of them, or thought of their return as long as they can get anything abroad, among the delights of the world. None so prodigiously wicked as those who are fed high with carnal pleasures. They are to the ungodly as the dung and ordure is to the swine which grows fat by lying in it; so their hearts grow gross and fat; their consciences more stupid and senseless in sin by them; whereas the comforts and delights that God gives unto a holy soul by the creature, turn to spiritual nourishment to his graces, and draw these forth into exercise, as they do others' lusts. Secondly, dregs of wrath. The Israelites had little pleasure from their dainties, when the wrath of God fell upon them, before they could get them down their throats. The sinner's feast is no sooner served in but divine justice is preparing to send up a reckoning after it, and the fearful expectation of this cannot but spoil the taste of the other. William Gurnall.