All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
According to the Hanafi School of jurisprudence, Mani is impure, and it is among the major impurities, but if it is dry, it is enough to purify one’s clothes from it by scratching it off them.
Al-Ikhtiyaar li-Ta’leel Al-Mukhtaar, which is one of the books of the Hanafi School, reads: “Anything that comes out of the human body that requires a person to purify himself from it, is a major impurity, like faeces, urine, blood, pus and vomit. There is no difference of opinion on this issue. The same applies to Mani as the Prophet said to ‘Aa’ishah: "If it is wet, then wash it, and if it is dry, then scratch it off (the clothes).”; and he said to ‘Ammaar ibn Yaasir, “The dress should be washed from Mani, urine and blood.” If it stained the body and then became dry; Al-Hasan narrated from Abu Haneefah that the body does not become pure by scratching it off. However, Al-Karkhi reported from our scholars that the body becomes pure, because this is something common that is hard to avoid, but scratching it off does not mean that it is pure; the correct opinion of Abu Haneefah is that the Mani decreases by scratching it off and thus it becomes permissible to pray in that state.” [End of quote]
For more benefit, please refer to Fataawa 81587, 85710 and 88600.
Allaah Knows best.