Chapter on Rules of Janabah and Methods of Purification

Then he, Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, said: "The minimum amount of water that suffices for ghusl of janabah in cases of necessity, such as severe cold or scarcity of water, is an amount like oil spread over the body, enough for wiping." This indicates the leniency under such conditions.