LXX Num 3:41

καὶ λήμψῃ τοὺς Λευείτας ἐμοί, ἐγὼ Κύριος, ἀντὶ πάντων τῶν πρωτοτόκων τῶν υἱῶν Ἰσραήλ, καὶ τὰ κτήνη τῶν Λευειτῶν ἀντὶ πάντων τῶν πρωτοτόκων ἐν τοῖς κτήνεσιν τῶν υἱῶν Ἰσραήλ.

You are to take the Levites for Me—I am the LORD—in place of all the firstborn of Israel, and the livestock of the Levites in place of all the firstborn of the livestock of the Israelites.”