How long does a knot have to be tied to be considered a "קשר של קימא". (Knot of permanence).
מחמת חסרון כיס Machmas Chesron Kis: Stamps, Envelopes, Etc;
הכנה לחול (Preparations for a Weekday): Is There a Limit to the Amount of Exertion Used When Doing the Action?;