From him, from Ahmad ibn Muhammad, from Al-Husayn, from Al-Qasim, from Al-Husayn ibn Abi Al-Ala, who said: I asked Abu Abdullah عليه السلام about a man who becomes junub (in a state of major ritual impurity) and has only enough water to perform wudu (ablution) for prayer. Should he perform wudu with the water or perform tayammum (dry ablution)? Imam عليه السلام said: "He should perform tayammum. Do you not see that half of the purification has been made obligatory upon him?"