Exodus 30:12

When thou takest the sum of the children of Israel after their number, then shall they give every man a ransom for his soul unto the Lord, when thou numberest them; that there be no plague among them, when thou numberest them.

Exodus 28:1

And take thou unto thee Aaron thy brother, and his sons with him, from among the children of Israel, that he may minister unto me in the priest’s office, even Aaron, Nadab and Abihu, Eleazar and Ithamar, Aaron’s sons.