Albert Barnes Commentary Proverbs 17:18

"A man void of understanding striketh hands, And becometh surety in the presence of his neighbor." — Proverbs 17:18 (ASV)

Compare the marginal reference. Since nothing is nobler than the self-sacrifice of the true friend (Proverbs 17:17), so nothing is more contemptible than the weakness which allows itself to be sacrificed for the sake of worthless associates.

In the presence of his friend – that is, “On behalf of” or “to his friend for some third person.”