1 Then Joshua summoned the Reubenites, the Gadites and the half-tribe of Manasseh 2 and said to them, “You have done all that Moses the servant of the Lord commanded, and you have obeyed me in everything I commanded. 3 For a long time now—to this very day—you have not deserted your fellow Israelites but have carried out the mission the Lord your God gave you. 4 Now that the Lord your God has given them rest as He promised, return to your homes in the land that Moses the servant of the Lord gave you on the other side of the Jordan. 5 But be very careful to keep the commandment and the law that Moses the servant of the Lord gave you: to love the Lord your God, to walk in obedience to Him, to keep His commands, to hold fast to Him and to serve Him with all your heart and with all your soul.”
From chapter five to chapter twenty-two, what happened in between? After their circumcision, they went and captured the land as God had promised. Then they divided the land among the tribes. The many battles were over and now the Reubenites, the Gadites and the half-tribe of Manasseh could return East of the Jordan to the land that Moses the servant of the Lord gave you on the other side of the Jordan.
As Joshua noted in verse 2 above, he said you have obeyed me in everything I commanded and also You have done all that Moses the servant of the Lord commanded. They kept their word and obeyed as they said they would earlier.
Joshua, almost tenderly, said be very careful to keep the commandment and the law that Moses the servant of the Lord gave you: to love the Lord your God, to walk in obedience to Him, to keep His commands, to hold fast to Him and to serve Him with all your heart and with all your soul. Not simply obey, but walk in obedience to Him. Not simply keep His commands, but to hold fast to Him and to serve Him with all your heart and with all your soul. If you were going to be able to walk in obedience to Him you will need to hold fast to Him, so do that hold fast to Him.
I do not think obedience would last without holding fast to Him and serving Him with all your heart and with all your soul as anything else would be going through the motions waiting for the ‘right time’ to disobey. The following verses indicate Joshua had faith they would be able to do so, at least for a period of time.
6 Then Joshua blessed them and sent them away, and they went to their homes. 7 (To the half-tribe of Manasseh Moses had given land in Bashan, and to the other half of the tribe Joshua gave land on the west side of the Jordan along with their fellow Israelites.) When Joshua sent them home, he blessed them, 8 saying, “Return to your homes with your great wealth—with large herds of livestock, with silver, gold, bronze and iron, and a great quantity of clothing—and divide the plunder from your enemies with your fellow Israelites.”
Then a great misunderstanding arose when the tribes on the East side of the Jordan built an imposing altar by the Jordan (v10). The other tribes thought they had built an altar in rebellion against Him (v16) and were concerned If you rebel against the Lord today, tomorrow he will be angry with the whole community of Israel (v18). Reuben, Gad and the half-tribe of Manasseh replied stating And let Israel know! If this has been in rebellion or disobedience to the Lord, do not spare us this day (v22). They were in fact not acting in disobedience, but did build an altar—but not for burnt offerings or sacrifices.’ 27 On the contrary, it is to be a witness between us and you and the generations that follow, that we will worship the Lord at his sanctuary with our burnt offerings, sacrifices and fellowship offerings. Then in the future your descendants will not be able to say to ours, ‘You have no share in the Lord.’
This pleased the other tribes and the Reubenites and the Gadites gave the altar this name: A Witness Between Us—that the Lord is God (v34). It is amazing how careful they were to hold fast to God and to want their future generations to do the same.