The third is that the hair of a dead animal is pure if the animal was pure while alive, such as a sheep or a mouse; but the hair of an animal that is impure while alive, such as a dog or a pig, is impure. According to most of Ahmad’s followers, this is the position he explicitly stated.
The strongest view is that all hair is pure—the hair of dogs, pigs, and other animals—unlike saliva. Accordingly, if a dog’s hair is wet and touches a person’s clothing, nothing is required of that person. This is the position of the majority of jurists, including Abū Hanīfah, Mālik, and Ahmad according to one of the two opinions reported from him. This is because material things are presumed pure: nothing may be declared impure or forbidden without evidence. As Allah Most High says:
“He has already explained to you what He has forbidden you, except that to which you are compelled by necessity.”
And Allah Most High says:
“Allah would never lead a people astray after guiding them until He makes clear to them what they must avoid.”
The Prophet, may Allah bless him and grant him peace, said in an authentic hadith:
“Among the Muslims whose offence against their fellow Muslims is greatest is someone who asks about something that was not forbidden, only for it to become forbidden because of his question.”
The Sunan collections contain a report from Salmān al-Fārisī attributed to the Prophet, though some transmit it as a statement of Salmān himself:
“What is lawful is what Allah has made lawful in His Book, and what is forbidden is what Allah has forbidden in His Book. Whatever He has remained silent about is among the things He has pardoned.”
That being so, the Prophet, may Allah bless him and grant him peace, said:
“To purify the vessel of any one of you when a dog laps from it, wash it seven times, the first time with earth.”
Another hadith says: “If a dog laps.” Thus, all the hadiths on this matter mention only lapping; they do not mention the rest of the dog’s body. Declaring those other parts impure therefore rests solely on analogy.