tn The form אַל־תִּתְהַלֵּל (’al-tithallel) is the Hitpael jussive negated; it is from the common verb “to praise,” and so in this setting means “to praise oneself” or “to boast.”
sn The verse rules out one’s overconfident sense of ability to control the future. No one can presume on the future.
2
sn The word “tomorrow” is a metonymy of subject, meaning what will be done tomorrow, or in the future in general.
3
sn The expression “you do not know” balances the presumption of the first line, reminding the disciple of his ignorance and therefore his need for humility (e.g., Matt 6:34; Luke 12:20; Jas 4:13–16).