The Shaykh (Al-Mufid), may Allah سبحانه وتعالى support him, narrated to me from Abu Al-Qasim Ja‘far bin Muhammad, from Muhammad bin Ya‘qub, from Ali bin Ibrahim, from his father, and Muhammad bin Isma‘il, from Al-Fadl bin Shadhan, all from Hammad bin ‘Isa, from Hariz, from Zurarah, who said: I said to Abu Ja‘far عليه السلام: "Will you not inform me how you came to know and say that the wiping is over part of the head and part of the feet?" Imam عليه السلام laughed and then said: "O Zurarah, the Messenger of Allah سبحانه وتعالى (peace and blessings be upon him and his family) said it, and it was revealed in the Book of Allah سبحانه وتعالى, the Exalted. Allah سبحانه وتعالى, the Exalted, says: 'Wash your faces' (Surah Al-Ma'idah 5:6), so we understood that the entire face should be washed. Then He سبحانه وتعالى said: 'And your hands to the elbows,' and then He سبحانه وتعالى separated the statements by saying: 'And wipe over your heads.' When He سبحانه وتعالى said, 'over your heads,' we understood that wiping over part of the head was sufficient due to the inclusion of the letter 'ba'. Then He سبحانه وتعالى connected the feet to the head just as He سبحانه وتعالى connected the hands to the face by saying: 'And your feet to the ankles.' So we understood, when He سبحانه وتعالى connected them to the head, that wiping over part of them was sufficient. Then the Messenger of Allah سبحانه وتعالى (peace and blessings be upon him and his family) explained this to the people, but they neglected it. Then He سبحانه وتعالى said: 'And if you cannot find water, then perform tayammum with clean earth: wipe your faces and your hands with it' (Surah An-Nisa 4:43). When He سبحانه وتعالى exempted ablution for those who could not find water, He سبحانه وتعالى replaced washing with wiping, for He سبحانه وتعالى said: 'Wipe your faces' and then connected to it: 'And your hands.' Then He سبحانه وتعالى said: 'From it,' meaning from the tayammum, because He سبحانه وتعالى knew that the entirety of the face would not be covered, as only part of the palm would contact the earth, and not all of it. Then He سبحانه وتعالى said: 'Allah سبحانه وتعالى does not intend to impose hardship on you' (Surah Al-Ma'idah 5:6), and hardship is difficulty and restriction."