Chapter on Rules of Janabah and Methods of Purification

Then he, Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, said: "The ghusl can be performed using a sa‘ of water, which is approximately nine Baghdadi pounds (about four litres), and this constitutes thorough washing (isbagh). Using less than this is sufficient for purification (taharah)." This emphasizes the importance of ensuring that water reaches all parts of the body during ghusl and highlights that a sufficient amount of water for ghusl is not excessively large, while thoroughness is encouraged.