Scholars agreed on a number of impurities that invalidate prayer, including the pig, with all its parts and organs; hair, bone, and skin; Because it is impure in itself, just as its tanned skin is impure, and the Malikis excluded the live pig's saliva, not the dead one, and its mucus, tears, and sweat, and they said that it is pure.
Islam commanded the Muslim to be pure and clean, and the need to rid him of filth, and in the idiomatic sense, cleanliness means removing impurity, so what is impurity?, And what impurities invalidate prayer? Impurity in the language means filth, and impure is dirty or impure, and in the tolerant Islamic law it is a specific filth that prevents the validity of prayer.

And the Muslim must guard against it first, and if it occurs to him, he must purify himself from it, in implementation of the command of God Almighty in His decisive Holy Book. Due to the importance of a Muslim being pure and free of impurity, the scholars of jurisprudence have placed impurities in the science of the branches of jurisprudence, as one of the chapters of the Book of Purity, which is confirmed by the purified Sunnah of the Prophet, as the Messenger of God, may God’s prayers and peace be upon him, said: (Purity is half of faith).