John Lightfoot on Luke 2:43

[And when they had fulfilled the days.] Here ariseth a question, Whether it was lawful to depart from Jerusalem before the seven days were ended? If not, why did Peter and Cleophas go away on the third day? If they might, how then is that precept to be understood about eating the unleavened bread throughout the whole seven days?

I. It is controverted amongst the doctors about that passage, Deuteronomy 16:6,7, "Thou shalt sacrifice the Passover at the even, at the going down of the sun, and thou shalt turn in the morning, and go into thy tents," whether it be lawful, after they had eaten the lamb, to go every one to his own house. This is denied, and that not without reason. For as it is in the Gloss, "On the day of the feast," (that is, the first day of the seven,) "the sabbatical limits forbade it." For on the feast day no man ought to exceed the bounds of a sabbath day's journey. "That therefore, (say they) that is said, 'Thou shalt go into thy tents,' is to be thus understood, 'Thou shalt go into thy tents that are without the walls of Jerusalem; but by no means into thine own house.'"

II. Was it lawful then to return home on the second day of the feast? No, it was not. For on that day was the general appearance in the court, and presentment of their offerings. And this seems hinted by R. Elhanani in another Gloss upon the place newly cited: "There were two reasons (saith he) of their lodging in Jerusalem: the one because of the feast day; the other because of the offering."

III. It was not unlawful to depart on the third day, if necessity of affairs required it. But as in many other cases the doctors were wont to speak, so might it be said in this it was much more commendable for them to abide in Jerusalem till all the seven days were ended; and that especially because of the last day, which was a festival or holy day.

"R. Jose the Galilean saith, There are three things commanded to be done in the feast; 1. the Chagigah; 2. the appearance in the court; 3. the rejoicing." The Chagigah or the peace offerings were on the first day; the appearance in the court was on the second day; the rejoicing might be on any day.

IV. In Moed Katon, a treatise that discourseth on things lawful or not lawful to be done in the intermedials of the feast, or in those days of the feast that were not kept holy; in the very entrance of that discourse there are several things allowed, which plainly argue absence and distance from Jerusalem.

As to eating unleavened bread, the precept indeed was indispensable, neither that any thing leavened should be eaten, nor that any leaven should be found in their houses for seven days together: but no one would say that this command was restrained only to Jerusalem. It is said in Jerusalem Kiddushin, the women's Passover is arbitrary: that is, the women's appearance at Jerusalem at the Passover was at pleasure. But let them not say that eating unleavened bread was arbitrary, or at the women's pleasure: for although they sat at home, and did not go to Jerusalem to the Passover, yet did they abstain from leaven in their own houses: the unleavened bread was eaten in every house.

VI. It seems from the very phraseology that Joseph and Mary continued at Jerusalem all the seven days; which was indeed generally done by others for devotion's sake. And then think what numerous companies of people must be going away to this or that country, yea, particularly, how great a crowd might be journeying, together with Joseph and Mary, towards Galilee. So that it may be less strange, if Jesus had not been within his parents' sight, though he had been among the crowd; nor that though they did not see him, yet that they should not suspect his absence.