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.
Yevamot 63bBabylonian Talmud
The Gemara quotes additional statements from the book of Ben Sira: Do not suffer from tomorrow’s trouble, that is, do not worry about problems that might arise in the future, as you do not know what a day will bring. Perhaps when tomorrow comes, the individual who was so worried will not be among the living, and he was consequently upset over a world that is not his. Prevent a crowd from inside your house, do not let many people enter, and do not even bring all your friends into your house. Make sure, however, that a crowd seeks your welfare, and that you have many allies. Reveal a secret to only one in a thousand, since most people are unable to keep a secret.
Notes and References
"... The following partial paragraph (with bullets added) from Davies and Allison is noteworthy: Both 6:34a and 34b appear to have been drawn from the well of common wisdom and probably go back ultimately to Egyptian proverbs ... Compare the following [the bullets have been added]:
• The Eloquent Peasant 183: ‘do not prepare for tomorrow before it is come. One knows not what evil may be in it’
• Instruction of Amen-em-Opet 19.11–13: ‘Do not spend the night in fear of the morrow. At dawn what is the morrow like? One knows not what the morrow is like’
• Proverbs 27:1: ‘Do not boast about tomorrow, for you do not know what a day may bring forth’
• b. Sanhedrin 100b / b. Yevamot 63b: ‘Do not fret over tomorrow’s troubles, for you do not know what a day may bring forth. Tomorrow may come and you will be no more and so you will have grieved over a world that is not yours’ ..."
Wright, Benjamin G. Praise Israel for Wisdom and Instruction: Essays on Ben Sira and Wisdom, the Letter of Aristeas and the Septuagint (p. 124) Brill, 2008