The two Israelites impose three conditions which Rahab must keep: (1) tie the red cord to the window (verse 18a); (2) gather all the family in the house and keep them there during the fighting (verses 18b-19); and (3) keep the whole arrangement a strict secret (verse 20).

When we invade your land is more literally “When we come into the land,” but the obvious reference is to an attack by the Israelites on the land and its people. Some translators prefer to leave the entire clause implicit.

Red cord translates the Hebrew phrase “cord of red thread”; in the Old Testament the Hebrew word translated “cord” occurs only here and in verse 21.

Some languages may require that the text specify whether the cord was supplied by the Israelite spies or whether it already belonged to Rahab. If it is assumed that the cord was given to her by the two men, one may translate “We are giving you this red cord for you to tie to your window when we invade your land.” In the report of how Rahab and her family were spared (6.22-25), no mention is made of the cord.

Quoted with permission from Bratcher, Robert G. and Newman, Barclay M. A Handbook on Joshua. (UBS Helps for Translators). New York: UBS, 1983. For this and other handbooks for translators see here .