1 Chronicles 12:8, 37-38

Some brave and experienced warriors from the tribe of Gad also defected to David while he was at the stronghold in the wilderness. They were expert with both shield and spear, as fierce as lions and as swift as deer on the mountains.

From the east side of the Jordan River—where the tribes of Reuben and Gad and the half-tribe of Manasseh lived—there were 120,000 troops armed with every kind of weapon. All these men came in battle array to Hebron with the single purpose of making David the king over all Israel. In fact, everyone in Israel agreed that David should be their king.