Numbers 3:50
Of the firstborn of the children of Israel took he the money; a thousand three hundred and threescore and five shekels, after the shekel of the sanctuary: Of the firstborn of the children of Israel took he the money; a thousand three hundred and threescore and five shekels, after the shekel of the sanctuary:
The sum taken from the firstborn of the children of Israel as their redemption price was one thousand three hundred and threescore and five shekels. That money was reckoned after the shekel of the sanctuary, which served as the standard by which its value was fixed. The sanctuary meant in that reckoning is the Lord's tabernacle, God's dwelling place.
The redemption of the firstborn continued after the priesthood was transferred from the firstborn to the Levites, and its proceeds went to the Levites. The payment belongs to the ceremonial arrangements appointed for worship. It stands as part of the evidence that the Aaronic priesthood was established by law for its appointed age, until the type met its antitype.