Joshua 9:15
"And Joshua made peace with them, and made a league with them, to let them live: and the princes of the congregation sware unto them."
Cross References (ranked by relevance)
2 Samuel 21:2
And the king called the Gibeonites, and said unto them; (now the Gibeonites were not of the children of Israel, but of the remnant of the Amorites; and the children of Israel had sworn unto them: and Saul sought to slay them in his zeal to the children of Israel and Judah.)
Joshua 11:19
There was not a city that made peace with the children of Israel, save the Hivites the inhabitants of Gibeon: all other they took in battle.
Exodus 23:32
Thou shalt make no covenant with them, nor with their gods.