John Gil elaborates on Proverbs 25:19:
Trusting in a treacherous man in time of trouble
is like a bad tooth or a foot that slips.
(Proverbs 25:19 ESV)
It is not good to put confidence in any man, not in princes . . . much less in an unfaithful, prevaricating . . . 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.