Verses 1-2 are linked in their vocabulary and topic, which is avoidance of self-praise. Verse 1 is very similar to an ancient Egyptian saying.

“Do not boast about tomorrow” is a warning not to brag about what you will do the next day. The thought behind this caution is that only God knows the future. A literal translation of “boast about tomorrow” may only mean not to “boast” that “tomorrow” will arrive. It is necessary to make clear in translation that a person should not “boast” (speak with excessive confidence) about what will happen “tomorrow” or what he will do “tomorrow”. For “boast” see 20.14.

“For you do not know what a day may bring forth”: In Hebrew “boast” in line 1 and “know” in this line have masculine singular second person pronouns. However, in translation “you” is best handled as inclusive and plural; or we may say, for example, “nobody knows” or “people don’t know.” “What a day may bring forth” means “what will happen” or “what each day may bring.” We may translate, for example, “Don’t brag about what you will do tomorrow because you do not know what will happen then.”

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Proverbs. (UBS Helps for Translators). New York: UBS, 2000. For this and other handbooks for translators see here .