Seven days you shall eat unleavened bread is identical with 12.15. And on the seventh day is similar to 12.16. There shall be a feast to the LORD is just two words in the Hebrew, “a [pilgrim] feast to Yahweh,” meaning “a festival to honor the LORD” (Good News Translation). Feast is discussed at 10.9.

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .