Remembering during the prayer that one did not perform istinja' after defecation

Question

Someone forgot to perform istinja' after defecation and remembered it during the prayer. What should he do?

Answer

As long as the impurity has not spread beyond its exit point (makhraj), istinja' is a sunna; when it has spread beyond the exit point and [its] amount is a dirham, removing it with water is wajib; and when it exceeds even the amount of a dirham, washing it with water is fard. So these are three cases. In the first case he should complete the prayer, and that is all.

Source: Fatawa Mahmudiyya

Preview. The full text opens with JavaScript enabled.