For we have heard how Yahweh dried up the water of the Red Sea before you, when you came out of Egypt; and what you did to the two kings of the Amorites, who were beyond the Jordan, to Sihon and to Og, whom you utterly destroyed.
The two spies did attach one condition to their promise, that being, that under no circumstance would the woman betray their mission  (Joshua 2:14).  Also, there was the agreement that the identity of Rahab's house would be indicated by the red cord.