Tying religious rulings to custom.

Mashhur: Tying religious matters to things that are not fixed, meaning to custom, is problematic because people’s customs differ in this regard, such as what is considered a small amount versus a large amount. As you mentioned, I do not know if this tying is permissible?

The Shaykh : Tying what to custom?
Mashhur: Tying [them] to custom in terms of the Shari'ah.

The Shaykh: No, it is not permissible.
Mashhur: There is a rule regarding tying... for example, what was said about the rulings of the prostration for forgetfulness after the closing salam, in the case of someone who forgot to prostrate or forgot a unit of prayer, for instance. They said that if he remembers after a long time, or among the opinions, after a short time, the person is confused between long and short. Likewise, the continuity of the prostration, which some require.