Proverbs 18:24

Solomon here recommends friendship to us, and shows, 1. What we must do that we may contract and cultivate friendship; we must show ourselves friendly. Would we have friends and keep them, we must not only not affront them, or quarrel with them, but we must love them, and make it appear that we do so by all expressions that are endearing, by being free with them, pleasing to them, visiting them and bidding them welcome, and especially by doing all the good offices we can and serving them in every thing that lies in our power; that is showing ourselves friendly. Si vis amari, ama - If you wish to gain affection, bestow it. - Sen. Ut ameris, amabilis esto - The way to be beloved is to be lovely. - Ovid. 2. That it is worth while to do so, for we may promise ourselves a great deal of comfort in a true friend. A brother indeed is born for adversity, as he had said, Pro 17:17. In our troubles we expect comfort and relief from our relations, but sometimes there is a friend, that is nothing akin to us, the bonds of whose esteem and love prove stronger than those of nature, and, when it comes to the trial, will do more for us than a brother will. Christ is a friend to all believers that sticks closer than a brother; to him therefore let them show themselves friendly.

— Matthew Henry's Concise Commentary (public domain)

A man . . . friendly--better, "A man . . . (is) to, or, may triumph (Psa 108:9), or, shout for joy (Psa 5:11), that is, may congratulate himself." Indeed, there is a Friend who is better than a brother; such is the "Friend of sinners" [Mat 11:19; Luk 7:34], who may have been before the writer's mind. Next: Proverbs Chapter 19

— Jamieson-Fausset-Brown Commentary (public domain)