661. More Permitted Tying

Shabbos 10:5

One may tie a bow on Shabbos because it will not be switched out for a knot. Therefore, if a rope breaks, one may take the two ends, wrap a linen cord around them and tie a bow.

Shabbos 10:6

One may tie a knot that is not of permanent nature for the sake of a mitzvah. For example, one may tie a knot to measure one of the Torah's measurements. One may only tie a harp string that breaks in the Temple, not elsewhere. A harp string may not be tied for the first time on Shabbos, not even in the Temple.