Gaebelein's Annotated Bible
Now the children of Reuben and the children of Gad had a very great multitude of cattle: and when they saw the land of Jazer, and the land of Gilead, that, behold, the place was a place for cattle;8. The Tribes of Reuben, Gad, Half-Manasseh and their Portion
1. The petition of Reuben and Gad (Numbers 32:1-5)
2. The rebuke by Moses (Numbers 32:6-15)
3. Their answer (Numbers 32:16-19)
4. Moses’ reply (Numbers 32:20-24)
5. The final agreement (Numbers 32:25-41)
Failure is now again manifested. Reuben and Gad looked upon the beautiful territory which had been taken from the two Amorite kings, Sihon and Og. As Reuben and Gad were especially rich in cattle and the territory was one of great fertility, they were anxious to possess the land. The half-tribe Manasseh evidently made the same request and joined Reuben and Gad (verse 33). A lengthy controversy followed between Moses and these tribes. Moses saw at once the evil which was connected with such a request. They despised the land of promise. God had commanded them to possess that land. By their request they showed readiness to disobey God. Furthermore by desiring the land of Jazer and Gilead they would become separated from their brethren; they would let them go to fight alone in the land. The whole request manifested selfishness.
Compare them with Lot and his selfish choice (Gen. 13). He lifted up his eyes and beheld all the plain of Jordan, that it was well watered, even as the garden of the Lord, He then chose the plain of Jordan. How he suffered for it we know well from the divine record. Reuben and Gad also looked upon the good land and with the same selfishness as Lot requested the land. Consult 1Chronicles 5:25-26 and 2Kings 15:29, to find out how their descendants had to pay for the selfishness of their ancestors. They went a whoring after the gods of the people of the land and were the first carried away into captivity.
We see in their behaviour the picture of the Christian who is worldly-minded, who walks according to the flesh. He does not enter into the promised land and prefers earthly things to spiritual things. The story of Christendom is also written here.