Shabbat: Permanent Knots

You may not tie permanent knots on Shabbat. A permanent knot is a knot intended to remain tied for at least 24 hours. Any strings you connect on Shabbat must be able to come undone by pulling on a single string, such as a bow.
Note Since opinions differ on what constitutes a permanent knot, we do not even tie knots that are intended to be untied, such as a double figure-eight knot.