Priest: Benefits of of the Firstborn
Source: Nav
Numbers 3:46–51
To redeem the 273 firstborn Israelites who outnumber the Levites, / you are to collect five shekels for each one, according to the sanctuary shekel of twenty gerahs. / Give the money to Aaron and his sons as the redemption price for the excess among the Israelites.”
Numbers 18:15, 16
The firstborn of every womb, whether man or beast, that is offered to the LORD belongs to you. But you must surely redeem every firstborn son and every firstborn male of unclean animals. / You are to pay the redemption price for a month-old male according to your valuation: five shekels of silver, according to the sanctuary shekel, which is twenty gerahs.