Matthew Poole and continuators on Deuteronomy 16:4

4 And there shall be no leavened bread seen with thee in all thy coasts seven dayes, neither shall there any thing of the flesh which thou sacrificedst the first day at even remain all night until the morning.

(i. e.) Of the Passeover properly so called and by these words plainly described; which circumlocution may seem to insinuate that the word Passeover ver. 1. was improperly used and therefore he chose rather to describe it, then to name it, lest the ambiguity of the word should occasion some mistake.

Marginal references: Exod. 34. 25.; Heb. leaven.; Exod. 12. 10.