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.

Wesley's Notes

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.

Scofield Reference Notes

[1] scarlet line

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

Jamieson-Fausset-Brown Bible Commentary

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.

Matthew Henry's Concise Commentary

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.