And it came to pass on the morrow
The day following the night, in which the above was transacted: that the firstborn said to the younger, behold, I lay yesternight with
my father;
informed her, that what they had contrived succeeded according to their wish, and therefore, for her encouragement to go on, proposes to take the same method again: let us make him drink wine this night also, and go thou in [and] lie
with him, that we may preserve seed of our father;
may have children by him, and so our family be kept up, from whence it may be hoped the Messiah will spring, (See Gill on Genesis 19:32).