Matthew Poole and continuators on Proverbs 17:18

18 A man void of understanding striketh hands , and becometh surety in the presence of his friend .

In token of his becoming Surety: of which Phrase, and of the thing it self, see on Prov. 6. 1. & 11. 15.

The Friend here is either 1. before, and to the Creditor. Or rather 2. before, and with, and for the Debtor, for whom, as being his Friend, he becomes Surety, as the manner of Friends is. See on Prov. 6. 3. And this Proverb is fitly placed after that v. 17. to intimate, that although the laws of Friendship oblige us to love and help our friends in trouble, as far as we are able, yet they do not oblige us to become Surety for them rashly, and above what we are able to pay, for by that means we make our selves unable to do good either to them, or to others, or to our selves.

Marginal references: Ch. 6. 1. & 11. 15.; Heb. heart.