Comentario sobre Exodo 13:4

בחדש האביב IN THE MONTH ABIB — But would we not know in which month they went out (even though it were not stated here)? But Moses spake to them as follows: See the kindness which God has bestowed on you — that He brought you forth in a month that is fitted for going out, not hot, nor cold nor rainy. In the same sense it says (Psalms 68:7) “He bringeth forth the prisoners בכשרות” i. e. in a month that is fitted (כשר) for going out (Mekhilta d'Rabbi Yishmael 13:4:1).

בחודש האביב, the reason that the Passover festival is to be observed in spring is so that it will coincide with the legislation of marking the lunar new year with the month of spring, the month of rejuvenation. Our sages have been very careful when calculating a permanent calendar to ensure that Passover never occurs before the spring equinox.

האביב; the time when the earliest harvests ripen. Compare the use of the word אביב in this context in Job 8,12 עודנו באבו לא יקטף, “while still tender not yet plucked.” The word also occurs in Song of Songs 6,11 in this senseלראות באבי הנחל, “to see the budding of the vale.’ The dagesh in the letter ב in the word באבי replaces the missing letter ב from the word אביב.