Proverbs 27:2
1 Do not boast about tomorrow; for you do not know what a day may bring forth. 2 Let another praise you, and not your own mouth; someone else, and not your own lips. 3 A stone is heavy and sand is weighty, but vexation by a fool is more burdensome than the two of them. 4 Wrath is cruel and anger is overwhelming, but who can stand before jealousy? 5 Better is open rebuke than hidden love. 6 Faithful are the wounds of a friend, but the kisses of an enemy are excessive. 7 The one whose appetite is satisfied loathes honey, but to the hungry mouth every bitter thing is sweet.
Matthew 6:2
1 “Be careful not to display your righteousness merely to be seen by people. Otherwise you have no reward with your Father in heaven. 2 Thus whenever you do charitable giving, do not blow a trumpet before you, as the hypocrites do in synagogues and on streets so that people will praise them. I tell you the truth, they have their reward! 3 But when you do your giving, do not let your left hand know what your right hand is doing, 4 so that your gift may be in secret. And your Father, who sees in secret, will reward you.
Notes and References
"... The active form, ἀπέχω has the general references: be distant from, keep away from, or to have or receive in full. In this latter sense it often occurs in receipts among the papyri, as G. Adolf Deissmann has demonstrated, shedding light accordingly on some uses in the New Testament. For example, in Matthew 6:2 Jesus speaks of hypocrites who publicly announce their giving of alms and have thus ἀπέχουσιν τὸν μισθὸν αὐτῶν (received their reward). However, it is the sense of keeping away or being distant which is pertinent to the current investigation ... As in the surrounding Hellenistic culture, the LXX also expresses disapproval of self-praise e.g. ἐγκωμιαζέτω σε ὁ πέλας καὶ μὴ τὸ σὸν στόμα: Let your neighbour and not your own mouth, praise you (Proverbs 27:2); similar disdain applies to the self-confident attitude of one who boasts about the future ..."
Kmetko, Susan E. The Function and Significance of Middle Voice Verbs in the Greek New Testament (p. 109, 166) Australian Catholic University, 2018