Numbers 32:20-22

Amplified Bible

²⁰ Moses replied, “If you will do as you say, if you will arm yourselves before the Lord for war, ²¹ and every armed man of yours will cross the Jordan before the Lord until He has driven out His enemies before Him, ²² and the land [west of the Jordan] is subdued before the Lord, then afterward you shall return and be blameless [in this matter] before the Lord and before Israel, and this land [east of the Jordan] shall be yours as a possession before the Lord.