King James Version (KJV)
Boast not thyself of to morrow; for thou knowest not what a day may bring forth.
Modern English
Do not boast about tomorrow, for you do not know what a day may bring.
Hebrew
אַל תִּֽתְהַלֵּ֥ל בְּי֣וֹם מָחָ֑ר כִּ֤י לֹ֣א תֵ֭דַע מַה יֵּ֣לֶד יֽוֹם׃
ʾal tithalel byvom maḥar kiy loʾ tedaʿ mah yeled yvom