Breadcrumb: Do you promise?

In Num. 32, the tribes of Gad and Reuben approach Moses and ask whether they can inherit the lands east of the Jordan river, instead of crossing it with the rest of the Israelites. Moses fumes at them, accusing them of being as bad as the scouts in Num. 13-14, who put the Israelites off the idea of even entering Canaan. No, the tribe leaders, say. We will go with you into battle, but we will leave our women, children, and cattle in fortified cities west of the Jordan. Moses eventually agrees to this arrangement, but only after the tribes promise... three times.