And she said, according to your words, so be it,.... She agreed, that if the conditions required were not performed, they would be quit of their oath, but if they were, she expected it would be fulfilled:

and she sent them away, and they departed; took their leave of each other:

and she bound the scarlet line in the window; immediately, as Abarbinel thinks, and in the sight of the spies, that they might see that she conformed to their direction, and that they might take notice where she fastened it; and that she herself might, at the sight of it, be put in mind of the design of it, and be an encouragement to her faith as to the safety of her and her father's house; and it being a thing so trifling and insignificant in itself, would not be taken notice of by the inhabitants, or be thought to be done with any design; though, according to the instruction of the spies, it seems as if it was to be done when they came into the land, and into the city, and which seems most likely that it was then done.

When Rahab had accepted all these conditions, she let the men go, and bound the red cord in the window. It is not to be supposed that she did this at once, but merely as soon as it was necessary. It is mentioned here for the purpose of bringing the subject to a close.

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.

2:21 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 neglect about it.

[1] scarlet line

The scarlet line of Rahab speaks, by its color, of safety through sacrifice. Heb 9:19,22.

21. she bound the scarlet line in the window-probably soon after the departure of the spies. It was not formed, as some suppose, into network, as a lattice, but simply to hang down the wall. Its red color made it conspicuous, and it was thus a sign and pledge of safety to Rahab's house, as the bloody mark on the lintels of the houses of the Israelites in Egypt to that people.

2:8-21 Rahab had heard of the miracles the Lord wrought for Israel. She believed that his promises would certainly be fulfilled, and his threatenings take effect; and that there was no way of escape but by submitting to him, and joining with his people. The conduct of Rahab proved that she had the real principle of Divine faith. Observe the promises the spies made to her. The goodness of God is often expressed by his kindness and truth, Ps 117:2; in both these we must be followers of him. Those who will be conscientious in keeping promises, are cautious in making them. The spies make needful conditions. The scarlet cord, like the blood upon the doorpost at the passover, recalls to remembrance the sinner's security under the atoning blood of Christ; and that we are to flee thereto for refuge from the wrath of a justly offended God. The same cord Rahab used for the saving of these Israelites, was to be used for her own safety. What we serve and honour God with, we may expect he will bless, and make useful to us.