Proverbs 25:19 (BSB)

Like a broken tooth or a foot out of joint is confidence in a faithless man in time of trouble.

From Proverbs 25. Also in the ESV.

Commentary on Proverbs 25:19

• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Proverbs 25:19: 1. The confidence of an unfaithful man (so some read it) will be like a broken tooth; his policy, his power, his interest, all that which he trusted in to support him in his wickedness, will fail him in time of trouble, Psa 52:7. 2.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Proverbs 25:19: Confidence in an unfaithful man in time of trouble,.... It is not good to put confidence in any man, not in princes, nor in the best of men; much less in an unfaithful, prevaricating, and treacherous man; and especially in a time of distress and trouble, depending on his help and assistance, which is leaning on a broken reed, and trusting to a broken staff.
• Keil & Delitzsch (Lutheran), Biblical Commentary on the Old Testament on Proverbs 25:19: Pro 25:19 19 A worthless tooth and an unsteady foot - Trust in a faithless man in the day of need. The form רעה (with Mercha on the antepenult), Isa 29:19, takes the place of an inf. absol.; רעה here (about the tone syllable of which Dechî does not decide, thus without doubt Milra) is certainly not a subst.: tooth of breaking (Gesen.); for how...