In verses 16 through 19 we have the promise of the two tribes, who had reasons for their choice. Those who have their own choice will always have much to say to justify their choice.
"They approached him and said, We will build sheepfolds here for our livestock and cities for our little ones" (v. 16). They were concerned for their livestock and their little ones, but they did not seem to think about the livestock and little ones of the other tribes.
"We ourselves will be ready and armed to go before the sons of Israel, until we have brought them to their place" (v. 17a). This word indicates that they thought of themselves as quite capable, able to bring all the people to their place. In their self-confidence they dared to make such a promise. Instead of saying, "until we have brought them to their place," they should have said, "until the Lord has brought them to their place."
"We will not return to our homes until the sons of Israel have inherited each his inheritance" (v. 18). This sounds fair, but it was nevertheless their own choice and therefore was not the best arrangement.
"We will not inherit with them on the other side of the Jordan and beyond, because our inheritance has come to us on this side of the Jordan to the east" (v. 19). This promise seems fair and reasonable.