Deuteronomy 3:18

And Moses said unto them, If ye will do this thing, if ye will go armed before the LORD to war, And will go all of you armed over Jordan before the LORD, until he hath driven out his enemies from before him, And the land be subdued before the LORD: then afterward ye shall return, and be guiltless before the LORD, and before Israel; and this land shall be your possession before the LORD. But if ye will not do so, behold, ye have sinned against the LORD: and be sure your sin will find you out. Build you cities for your little ones, and folds for your sheep; and do that which hath proceeded out of your mouth.

And to the Reubenites, and to the Gadites, and to half the tribe of Manasseh, spake Joshua, saying, Remember the word which Moses the servant of the LORD commanded you, saying, The LORD your God hath given you rest, and hath given you this land. Your wives, your little ones, and your cattle, shall remain in the land which Moses gave you on this side Jordan; but ye shall pass before your brethren armed, all the mighty men of valor, and help them; Until the LORD have given your brethren rest, as he hath given you, and they also have possessed the land which the LORD your God giveth them: then ye shall return unto the land of your possession, and enjoy it, which Moses the LORD's servant gave you on this side Jordan toward the sunrising.

And the children of Reuben, and the children of Gad, and half the tribe of Manasseh, passed over armed before the children of Israel, as Moses spake unto them:

Then Joshua called the Reubenites, and the Gadites, and the half tribe of Manasseh, And said unto them, Ye have kept all that Moses the servant of the LORD commanded you, and have obeyed my voice in all that I commanded you: Ye have not left your brethren these many days unto this day, but have kept the charge of the commandment of the LORD your God. And now the LORD your God hath given rest unto your brethren, as he promised them: therefore now return ye, and get you unto your tents, and unto the land of your possession, which Moses the servant of the LORD gave you on the other side Jordan. But take diligent heed to do the commandment and the law, which Moses the servant of the LORD charged you, to love the LORD your God, and to walk in all his ways, and to keep his commandments, and to cleave unto him, and to serve him with all your heart and with all your soul. So Joshua blessed them, and sent them away: and they went unto their tents. Now to the one half of the tribe of Manasseh Moses had given possession in Bashan: but unto the other half thereof gave Joshua among their brethren on this side Jordan westward. And when Joshua sent them away also unto their tents, then he blessed them, And he spake unto them, saying, Return with much riches unto your tents, and with very much cattle, with silver, and with gold, and with brass, and with iron, and with very much raiment: divide the spoil of your enemies with your brethren. And the children of Reuben and the children of Gad and the half tribe of Manasseh returned, and departed from the children of Israel out of Shiloh, which is in the land of Canaan, to go unto the country of Gilead, to the land of their possession, whereof they were possessed, according to the word of the LORD by the hand of Moses.