Exodus 12:1-2

The Lord spake unto Moses Or had spoken before what is related in the foregoing chapter, if not also before the three days' darkness: but the mention of it was put off to this place, that the history of the plagues might not be interrupted. This month shall be to you the beginning of months That is, the first and principal month of the year. It was called Abib, (Exodus 13:4; Exodus 23:15,) which signifies an ear of corn, because then the corn was eared. It answers nearly to our March. Before this time, the Jews, like most other nations, began their year about the autumnal equinox, in the month Tisri, answering to our September, after their harvest and vintage. But in commemoration of this, their signal deliverance out of Egypt, their computation, at least as to their feasts and sacred things, was from the month Abib. And therefore, what was before their first month, now became their seventh. The beginning of their civil year, however, appears still to have been reckoned as before. We may suppose that while Moses was bringing the ten plagues upon the Egyptians, he was directing the Israelites to prepare for their departure at an hour's warning. Probably he had, by degrees, brought them near together from their dispersions, for they are here called the congregation of Israel; and to them, as a congregation, orders are here sent.