In 2:243:22 Moses spoke about the defeating of King Sihon and King Og and the taking possession of their lands east of the Jordan. Sihon was the king of Heshbon, and Og was the king of Bashan. It was not a small matter for the children of Israel to defeat these kings and to take possession of their lands. This must have been a joy to Moses.
To defeat King Sihon and King Og was to defeat the two gate guards of the land of Canaan.
After the children of Israel defeated Sihon and Og, they took possession of their lands, which were east of the Jordan. Moses said, "At that time we took the land from the hand of the two kings of the Amorites who were across the Jordan, from the valley of the Arnon to Mount Hermon" (3:8). This was the beginning of the taking possession of the good land.
The land taken from Sihon and Og was given to the tribes of Reuben and Gad and the half-tribe of Manasseh as the firstfruit of the enjoyment of the God-promised good land (3:12-20).
In 3:21 and 22 Moses said, "I commanded Joshua at that time, saying, Yours are the eyes that have seen all that Jehovah your God has done to these two kings; so will Jehovah your God do to all the kingdoms into which you are about to cross over. Do not fear them, for it is Jehovah your God who is fighting for you." This word indicates that the defeating of Sihon and Og and the taking possession of their lands were a security to the victory and possession of the remainder of the God-promised good land.