Numbers 28:16

And in the fourteenth day of the first month
The month Nisan, as the Targum of Jonathan or Abib, which, upon the Israelites coming out of Egypt, and on that account, was made the first month; otherwise Tisri or September was the first month, see ( Exodus 12:2 ) ( 13:4 ) ,

[is] the passover of the Lord;
a feast in which a lamb was killed and eaten, in memory of the Lord's passing over the houses of the Israelites, when he slew the firstborn in Egypt; see ( Exodus 12:6 Exodus 12:18 Exodus 12:23 Exodus 12:27 ) .