The children of Reuben and Gad requested to settle where the pastures would be good for their flocks. Moshe was critical, seeing that they valued their property above their children. He reminded them that their fathers were among those who had perished in the desert for their negative appraisal of the reports of the 12 spies. The people of Reuben and Gad then committed to help the Israelites conquer the land and remained in solidarity for a further seven years.
R’ Eli Munk wrote that the agreement the 2 tribes made was an example of the legal characteristics of a conditional contract. Firstly, the conditions were expressed both positively and negatively- “you shall cross the Jordan” and “but if you do not do so”. Secondly, the fulfilment of the condition was stated before the statement of the consequence- “if you do this thing” and “this land will be a heritage for you”. Thirdly, the positive condition was stated before the negative condition. Fourthly, the condition and the consequence involved different objects. The conquering of the land had no direct connection with taking possession of the territories on the east side of the Jordan. Lastly, the consequences could be fulfilled by the parties themselves or their authorised representatives. In this case, Moshe authorised Joshua to grant the eastern territories once Canaan was conquered.
The children of Reuben and Gad indicated they would cross over the river “armed before G-d”. R’ Munk quoted R’ Bachya who pointed to the verse beginning and ending with the letter “nun” and contains symbolic references to the thirteen letter name of G-d, which guards against the fear of the enemy. “Armed before G-d” indicates the sense in which their faith in G-d enabled them to fear nothing else.
Half of the tribe of Menashe were also allocated to the east side of the Jordan, and Rambam pointed out that this kept Reuben and Gad in touch with the rest of the people of Israel. Nevertheless they were most vulnerable when Israel was under attack in the future.