John Gill's Exposition of the Whole Bible
Proverbs 24:17
Rejoice not when thine enemy falleth,.... These words are spoken not to the wicked man, Proverbs 24:15; but to the just man, or Solomon's son, or the children of Wisdom; for by the "enemy" is meant such who are at enmity with the people of God, as the seed of the serpent, and those after the flesh, are: and when these "fall", saints should not "rejoice"; as when they fall into sin; for so to do would be to act as wicked "charity [which] rejoiceth not in iniquity",
1 Corinthians 13:6: or rather when they fill into calamity and distress; for this is also the part which wicked men act towards the people of God, and should not be imitated in; see Obadiah 1:12. Joy may be expressed at the fall of the public enemies of God and his people, as was by the Israelites at the destruction of Pharaoh and his host, Exodus 15:1; and as will be by the church at the destruction of antichrist, and which they are called upon to do, Revelation 18:20; partly on account of their own deliverance and safety, and chiefly because of the glory of God, and of his justice displayed therein; see
Psalms 58:10; but as private revenge is not to be sought, nor acted, so joy at the calamity and ruin of a private enemy, or a man's own enemy, should not be expressed; but rather he is to be pitied and helped; see
Proverbs 25:21; for to love an enemy, and show regard to him, is the doctrine both of the Old and of the New Testament;
and let not thine heart be glad when he stumbleth; even secret joy should not be indulged, gladness in the heart, though it does not appear in the countenance, and is not expressed in words; no, not at the least appearance of mischief, when he only stumbles and is ready to fall; and much less should there be exultation and rejoicings made in an open manner at the utter ruin of him.