Muhammad, from his father, from Muhammad ibn al-Hasan al-Saffar, from Ahmad ibn Muhammad ibn Isa, from al-Husayn ibn Sa‘id, from Hammad, from Hariz, from Zurara and Muhammad ibn Muslim. I said: "What about a man who does not find water, and the time for prayer arrives, so he performs tayammum and prays two rak‘ahs, then finds water? Should he nullify the two rak‘ahs or stop them, perform ablution, and then pray?" Imam عليه السلام said: "No, rather he should continue his prayer and not nullify it because he started it while in a state of purification by tayammum." Zurara said: "I asked Imam عليه السلام: What if he entered the prayer with tayammum, prayed one rak‘ah, then invalidated his purification and found water?" Imam عليه السلام said: "He should leave, perform ablution, and continue from where he left off in the prayer he had started with tayammum."