Verses 10 to 12 of Joshua 4.

The priests who were carrying the Ark stood in the middle of the river until all of the Lord’s commands that Moses had given to Joshua were carried out. Meanwhile, the people hurried across the riverbed.  And when everyone was safely on the other side, the priests crossed over with the Ark of the Lord as the people watched. The armed warriors from the tribes of Reuben, Gad, and the half-tribe of Manasseh led the Israelites across the Jordan, just as Moses had directed.