Genesis 29:28

And Jacob did so, and fulfilled her week
The week of the days of the feast of Leah, as the Targum of Jonathan adds; he agreed to it; during which time he cohabited with Leah as his wife, and which confirmed the marriage: how justifiable this was, must be left. The marrying of two sisters was forbidden by the law of Moses, ( Leviticus 18:18 ) ; and polygamy was not allowed of in later times, and yet both were dispensed with in times preceding; and there seems to be an overruling Providence in this affair, which oftentimes brings good out of evil, since the Messiah was to spring from Leah, and not Rachel; (See Gill on Genesis 29:35); and having more wives than one, and concubines also, seems to be permitted for this reason, that Jacob might have a numerous progeny, as it was promised he should: and indeed Jacob was under some necessity of marrying both sisters, since the one was ignorantly defiled by him, and the other was his wife by espousal and contract; and though he had served seven years for her, he could not have her without consenting to marry the other, and fulfilling her week, and serving seven years more; to such hard terms was he obliged by an unkind uncle, in a strange country, and destitute:

and he gave him Rachel his daughter to wife also;
not after seven years' service, as Josephus ^F21 thinks, but after the seven days of feasting for Leah; though on condition of the above service, as appears from various circumstances related before the seven years' service could be completed; as his going in to Rachel, ( Genesis 29:30 ) ; her envying the fruitfulness of her sister, ( Genesis 30:1 ) ; giving Bilhah her handmaid unto him, ( Genesis 30:3 ) ; and the whole series of the context, and life of Jacob.