Then it shall be, on the day he causes his sons to inherit that which he has, that he may not make the son of the beloved the firstborn before the son of the hated, the firstborn.
English: “On the day he causes them to inherit” — this teaches that the law of inheritances is by day and not by night.
On the daf / in context: Inheritance distribution is treated like a judicial act. If the father assigns the portions by day the assignment stands as a completed judgment; if by night the matter must still be confirmed before a court.
Type of Learning
Derash on the word “be-yom.”
What Is Learned
The formal assignment of inheritance portions is performed by day, not by night.