Exodus 13:2
Sanctify unto me all the firstborn, whatsoever openeth the womb among the children of Israel, both of man and of beast: it is mine. Sanctify unto me all the firstborn, whatsoever openeth the womb among the children of Israel, both of man and of beast: it is mine.
Sanctify unto me all the firstborn means that every firstborn among Israel, both of man and of beast, every firstborn male and every firstborn son in each household, belonged to the Lord to be sanctified, consecrated and set apart to Him. The command was given after the Lord spared Israel's firstborn when He struck and slew the firstborn of Egypt and passed over the blood-marked homes of Israel. The dedication and presentation of the firstborn was a memorial of that wonderful deliverance from Egyptian bondage, keeping the deliverance in memory. Although the tribe of Levi later served in the sanctuary in place of Israel's firstborn, the firstborn remained the Lord's and had to be redeemed by a ransom.
The dedication reaches back to the earliest times and acknowledges God's gift of heaven's First-born to save sinners. The firstborn son was devoted to the priesthood as a representative of Christ among people. The deliverance it memorialized prefigured a greater deliverance to be wrought by God's only begotten Son, with the lamb's blood and the blood sprinkled on the doorposts representing the blood of Christ which alone has power to save the world.
The law provides the setting for Jesus being presented to the Lord in Jerusalem about forty days after His birth, as each family's firstborn son was presented at the temple. As humanity's substitute He conformed to the law in every particular. Jesus' presentation in obedience to the law teaches obedience by example.