Where does the Bible say not to worry about tomorrow?
It is in Matthew 6:34 · King James Version
«Take therefore no thought for the morrow: for the morrow shall take thought for the things of itself. Sufficient unto the day is the evil thereof.»Read the chapter Matthew 6 →
See also
Philippians 4:6
Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God.
1 Peter 5:7
Casting all your care upon him; for he careth for you.