Deuteronomy 21:17

Double portion. If a person left six children, his effects were divided into seven equal parts, and the eldest son received two of them, though others think that he was entitled to one-half of the whole, (Calmet) in order to enable him to support the dignity of the family, (Haydock) and the greater expenses which he had to incur for sacrifices and solemn feasts. (Grotius) --- If he were dead, his children or heirs were entitled to his portion. This was the prerogative of the first-born, 1 Paralipomenon v. 2. (Selden) --- The right to the priesthood, if they might have claimed it before the law, was now given to the family of Aaron. Females had no privilege above one another. They received equal shares, when there was no male issue, Numbers xxxvi. (Haydock) --- First. Hebrew, "the beginning of his strength." See Genesis xlix. 3.