Charles Ellicott Commentary Exodus 13:4

"This day ye go forth in the month Abib." — Exodus 13:4 (ASV)

The month Abib. —Abib means “green ears of corn,” or “greenness;” and the month of Abib was that in which the wheat came into ear, and the earth generally renewed its greenery. It was a “vague,” or shifting month, since it properly began with the day of the full moon that followed next after the vernal equinox. It retained its name until the Babylonian captivity, when the Babylonian name Nisan superseded the original one (Nehemiah 2:1; Esther 3:7).