Exodus 34:18
The feast of unleavened bread shalt thou keep. Seven days thou shalt eat unleavened bread, as I commanded thee, in the time of the month Abib: for in the month Abib thou camest out from Egypt. The feast of unleavened bread shalt thou keep. Seven days thou shalt eat unleavened bread, as I commanded thee, in the time of the month Abib: for in the month Abib thou camest out from Egypt.
The command to keep the feast of unleavened bread belongs to the words of the covenant given while Moses spent a second period of forty days and nights alone on the mount. During that time he met with no one and was miraculously sustained without ordinary support. At God's command he had prepared two tables of stone and carried them to the summit, where the Lord Himself wrote upon them the words of the covenant, the Ten Commandments. That inscribed covenant was the pledge of God's reconciliation and restored favor to Israel, and its glory was reflected in the dazzling light that shone from Moses' face when he came down.