Musannaf Ibn Abi Shaybah

Hazrat Ibrahim says that it was said among the predecessors to wash the hair and to let water reach the skin during major ritual impurity (janabah).

Hasan says that there is impurity under every hair, so wet the hair and let the water reach the skin.

Hazrat Abu Bakhtari narrates that Hazrat Hudhaifa (may Allah be pleased with him) bent his head and came out, and said: "Under every hair where water does not reach, impurity remains, but people are negligent about this. Therefore, I have become an enemy of my own hair, as you can see."

Hazrat Ali (may Allah be pleased with him) narrates that the Messenger of Allah said: "Whoever, while performing the ritual bath of Janabah, leaves even an area equal to a single hair on his body unwashed, then such and such will be done to him in Hell." Hazrat Ali (may Allah be pleased with him) says, after that I became an enemy of my own hair. Hazrat Ali (may Allah be pleased with him) used to shave his head.

Hasan says that there is impurity (janabah) under every hair, and he says that Hazrat Abu Hurairah used to say: I wet the hair and make the water reach the skin.

Hazrat Nafi' states that Hazrat Ibn Umar (may Allah be pleased with them) when performing ghusl after janabah, would let water enter his eyes and insert his fingers into his navel.