'Scarlet' in the Bible

Behold, when we come into the land, thou shalt bind this line of scarlet thread in the window which thou didst let us down by: and thou shalt bring thy father, and thy mother, and thy brethren, and all thy father's household, home unto thee.

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.