Joshua 22:27
But that it may be a witness between us, and you, and our generations after us, that we might do the service of the LORD before him with our burnt offerings, and with our sacrifices, and with our peace offerings; that your children may not say to our children in time to come, Ye have no part in the LORD.
The altar is a witness only, not a place on which to present offerings or sacrifices. It is made after the pattern of the altar at Shiloh, to declare that its builders are joined to the living God. It testifies that the tribes settled east of the Jordan, though living apart from the sanctuary across the river, belong to the same people and share with the rest of Israel in serving the Lord. It stands for them and their descendants after them, so that in time to come children on the west cannot say to children on the east that they have no part in the Lord.
The act is honestly meant to preserve connection with the Lord, yet it is mistaken for defection from Him, and that misunderstanding about worship threatens the unity of God's people. Zeal to guard true worship becomes unjust suspicion when judgment is passed before the facts are learned.
The wise and courteous answer of the eastern tribes turns aside a conflict that could have proved fatal. Those who are unjustly suspected or censured should likewise answer with meekness and forbearance rather than with anger or retaliation.