The Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, said: "Purification that removes the state of ritual impurity is of two types: One is ghusl (ritual washing) and the other is wudu (ablution). Ghusl is required in the case of janabah (major ritual impurity), which occurs due to two things: - One is the emission of seminal fluid, whether in sleep or wakefulness, and in all situations; - Other is intercourse involving penetration, whether accompanied by emission or not. Ghusl is also required for women after menstruation (hayd) when the bleeding ceases, and during excessive uterine bleeding (istihadah) when the blood overwhelms them. I will explain the rulings regarding this in its appropriate place, if Allah سبحانه وتعالى wills. Additionally, ghusl is obligatory for postnatal bleeding (nifas) when the bleeding ends. Ghusl is also obligatory for deceased humans and for those who touch them, as we have also explained. The details of this will be clarified later in the appropriate section, if Allah سبحانه وتعالى, the Exalted, wills. Then, the Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, said: 'As for the other forms of ritual impurities previously mentioned, wudu is obligatory for them and not ghusl.' This has already been explained in detail."
Commentary #1