Among the Israelites the first-born son possessed special privileges. He succeeded his father as the head of the house and received as his share of the inheritance a double portion. Israel was the Lord’s firstborn (
FIRST-BORN (בְּכֹר, H1147, πρωτότοκος, G4758, meaning first in sequence to be born or, fig., first in rank, preeminent).
J. B. Lightfoot, Saint Paul’s Epistles to the Colossians and to Philemon (1900); R. deVaux, Ancient Israel (1961), 41, 42.
International Standard Bible Encyclopedia (1915)
furst’-born, furst’-ling (bekhor; prototokos):
NOTE--The custom of redeeming the firstborn son is preserved among the Jews to this day. After thirty days the father invites the "Kohen," i.e. a supposed descendant of Aaron, to the house. The child is brought and shown to the "Kohen," and the father declares the mother of the child to be an Israelite. If she is a "Kohen," redemption is not necessary. The "Kohen" asks the father which he prefers, his child or the five shekels; the father answers that he prefers his son, and pays to the "Kohen" a sum equivalent to five shekels. After receiving the redemption-money, the "Kohen" puts his hands on the child’s head and pronounces the Aaronite blessing (