Joshua 2:18

Behold, [when] we come into the land
The land of Canaan, and into this city, into that part of it, as the Septuagint, where her house was, meaning not themselves only, but the people of Israel they belonged to:

thou shall bind this line of scarlet thread in the window which thou
didst let us down by;
the word by refers either to the scarlet thread they were let down by, said to be a cord, ( Joshua 2:15 ) ; and therefore must be a line twisted with various scarlet threads, as Kimchi; who observes, that according to the Targum, it was the border of a red garment; or to the window through which they were let down, as the Septuagint version; it may refer to both, and the sense be, that the same twisted cord of scarlet thread they were let down by should be bound to the same window they were let down through; only this objection there is to the same window, that it was not towards the city, and so not to be seen when they came into it, but looked over the wall without the city: now as Rahab was an instance of the salvation of sinners by the grace of God, for she was a sinner by birth, by practice, and a notorious one; she was an instance of distinguishing grace, of free and efficacious grace, a singular instance of it; and became a true penitent, a real believer, was a justified person, and saved: so the scarlet thread was an emblem of the blood of Christ, by which salvation is; redemption and all the blessings of grace are through it; justification, remission of sin, reconciliation, and atonement, and safety, and protection from avenging justice, and wrath to come, are only by it: likewise the spies, who are also called "messengers", ( James 2:25 ) ; may represent the ministers of the Gospel, who are the messengers of Christ, and the churches, are sent out by him the antitypical Joshua, men of wisdom, courage, and valour, and are sent as spies to bring to light men and things, who direct to the way of salvation and give the same token of it, ( Mark 16:16 ) ;

and thou shall bring thy father, and thy mother, and thy brethren, and
all thy father's household home unto thee;
into her house, where the scarlet thread was bound, and where only they would be safe, as the Israelites were in the houses where the blood of the paschal lamb was sprinkled, ( Exodus 12:23 ) ; and so they are safe, and they only, who are under the blood of sprinkling, and partake of the virtue of it.