Is purification from impurity a condition for the validity of prayer, regarding the quantity of impurity?
Chapter on Praying with Impurity and Other Matters
Al-Mughni
Book of Prayer
Primary text
Purification from impurity is a necessary condition for the validity of prayer. There is no distinction regarding the quantity of impurity, except for specific exceptions that will be mentioned later. Scholars such as Malik, Al-Shafi'i, and Abu Thawr maintain that even small amounts of urine, equivalent to the head of a needle, do not warrant exemption. The evidence against exemption includes the general command of Allah: {And your garments, purify them} (Quran 81:4), and the Prophet's saying: 'Keep yourselves away from urine, for the majority of the punishment in the grave is from it.' Furthermore, urine is an impurity whose removal is not overly burdensome, thus removal is obligatory, similar to a large amount.
Supporting text
Abu Hanifa stated that small amounts of all impurities are excused because the worshipper usually exerts effort in wiping during the purification of the private parts (istinja'), and if small amounts were not excused, wiping would not suffice for them as it does for large amounts. Exemption is also justified because it is difficult to avoid completely, analogous to blood.