The tribes highlighted their family connection—their common ancestry—with David. Like him, they were also descended from Jacob and thus the expectation that they were brothers who belong together.1 The fact that David was a brother Israelite meant that he could legitimately serve as king (Deuteronomy 17:15).2
1 Then all the tribes of Israel came to David at Hebron and said, “Behold, we are your bone and flesh.