Matthew Poole and continuators on Joshua 2:21

21 And she said, According unto your words, so be it. And she sent them away, and they departed: and she bound the scarlet line in the window .

Forthwith, partly that the Spies might see it hung out before their departure, and so the better know it at some distance; partly lest some accident might occasion a mistake or neglect about it; and partly for her own comfort, it being pleasant and encouraging to her to have in her eye the pledg of her deliverance.