Numbers 3:12
When God miraculously destroyed all the first-born of the Egyptians, (Ex 12:29,) he spared those of the Israelites; and, in commemoration of that event, he was pleased to appoint that all the first-born males "should be set apart unto himself." (Ex 13:12-16.) God is here pleased to relinquish this claim, and to appoint the whole tribe of Levi to attend his immediate service in their stead.
Numbers 26:5
firstborn <01060> [the eldest.]
[thy children.]
Numbers 36:12
families ................... family <04940> [into the families. Heb. to some that were of the families.]
