Números 32:20

if ye will go armed before the Lord... — The same verb and the same preposition are here used which are used in Números 32:17. It may be inferred from this expression that the army of the Israelites was regarded as the army of the Lord; and it seems probable that there is a reference to the ark of the Lord as being carried on certain occasions into the war. If the order of march prescribed in the second chapter of this Book was still observed, there may be a reference to the fact that the tribes of Reuben and Gad, which encamped on the south side of the Tabernacle, immediately preceded the ark (see Números 10:18), just as those of Ephraim, Benjamin, and Manasseh immediately followed it (Salmos 80:2). At the time of the passage of the Jordan, the priests who bare the ark stood still in the river until the whole of the people had passed over “before the ark of the Lord” (Josué 4:5; Josué 4:11); but at the siege of Jericho it appears that the ark was carried in the midst of the host, some of the armed men going before it, and some following after it (Josué 6:9). If this is the true meaning of the word “before the Lord,” it was natural that the Reubenites, or their spokesman, should first use the words “before the children of Israel” in Números 32:17, and should not adopt the expression “before the Lord,” as in Números 32:32, until it had been previously employed by Moses.