Deuteronomy 16:1

The month of Abib. Literally, “the month of the young ears of grain” (Ex. 9:31; Lev. 2:14). This Jewish month, later called Nisan, began between late March and late April. Abib was appointed by God the first month of the ecclesiastical Israelite year (Ex. 12:2; cf. 13:4; 34:18).

The passover. Of the three commanded annual feasts the Passover was the first (Ex. 23:14-17). It was kept in Abib, or Nisan, for that was the month in which God brought Israel out of the land of Egypt. For seven days the people ate unleavened bread, as upon their hurried departure from Egypt (see on Ex. 12:34). No leaven was to remain in their houses, nor any of the Passover lamb after the first night. After the Passover animal had been eaten, the people returned to their tents. For six days they ate unleavened bread, and held a convocation on the seventh day, which was observed as a sabbath (see also Ex. 12:1-28).

By night. It was early morning (PP 281) when the children of Israel actually left Egypt (Ex. 12:29-34). The command to prepare for instant departure, and Pharaoh’s demand that they go immediately, were given the night before (Ex. 12:11, 12,31-33).