G2405–ἱερατεία–hierateia

it fell to his lot--according to the custom of the priesthood--to go into the Sanctuary of the Lord and burn the incense;

ἱερατείας hi'erateias “priesthood”

And those of the descendants of Levi who receive the priesthood are authorized by the Law to take tithes from the people, that is, from their brethren, though these have sprung from Abraham.

ἱερατείαν hi'erateian “priestly office”