Proverbs 27:1
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?
Matthew 6:34
31 So then, don’t worry saying, ‘What will we eat?’ or ‘What will we drink?’ or ‘What will we wear?’ 32 For the unconverted pursue these things, and your heavenly Father knows that you need them. 33 But above all pursue his kingdom and righteousness, and all these things will be given to you as well. 34 So then, do not worry about tomorrow, for tomorrow will worry about itself. Today has enough trouble of its own.
Notes and References
"... The immediate source of both parts of the Matthaean saying is probably in Jewish proverbial lore. Strack-Billerbeck quotes Sanhedrin 100b, ('Fret not over tomorrow's trouble, for thou knowest not what a day may bring forth, and peradventure tomorrow he is no more: thus he shall be found grieving over a world that is not.'); to illustrate the second part they quote Berakhot 9b, ('He [Moses] said to him: Lord of the Universe, sufficient is the evil in the time thereof') Philip A. Micklem in his 'Westminster Commentary' cites, as other instances of the use of popular sayings by Jesus, Matthew 9:12; 13:57; Luke 4. It may be suggested, however, that the ultimate source of the first part of the Matthaean saying is the wisdom of Egypt (compare Proverbs 27:1) ..."
Griffiths, J. Gwyn Wisdom about Tomorrow (pp. 219-221) Harvard Theological Review, 1960