The story
From Matthew 6:34 in the King James Version of the Bible (spelling modernized): “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.” The phrase is a translation of Ancient Greek ἀρκετὸν τῇ ἡμέρᾳ ἡ κακία αὐτῆς (arketòn tēî hēmérāi hē kakía autês), and there is a parallel rabbinical expression in the Babylonian Talmud, דיה לצרה בשעתה (“the suffering of the (present) hour is enough for it”).
Etymology from Wiktionary, CC BY-SA 4.0.