Exodus 13:2

All the firstborn. This command was given on the very day of the Exodus (see ch. 12:51). The Hebrew word here used limits the command to first-born males, who alone had been in danger from the tenth plague. The additional explanation, “whatsoever openeth the womb,” shows that only those first-born sons were meant who were at the same time their mothers’ first-born children. Their consecration was closely connected with the Passover. Inasmuch as the Lord had delivered the first-born of Israel, they became His special property and were to be dedicated to Him.