In the fourteenth day of this month,.... The first month, the month Nisan or Abib, answering to part of our March:at even ye shall keep it, in his appointed season: between the two evenings, Ex 12:6; and even if it fall on the sabbath day, as Jarchi; and this was a sabbath day, according to the Jewish writers :according to all the rites of it, and according to all the ceremonies thereof shall ye keep it; the former of these, according to Jarchi, respects the lamb, and the requisites of it, that it should be without blemish, a male, and of the first year; and the latter, according to him and others, the removal of the leaven, and the seven days of unleavened bread, and the eating of the lamb with bitter herbs: they take in no doubt all that were prescribed by the original law, except the sprinkling of the blood on the doorposts, and also eating the passover in haste, with their loins girt, and shoes on their feet, and staves in their hands; though some think these latter might be observed at this time, when they were unsettled.
Seder Olam Rabba. c.