• And I heard Ishaq say: "When you perform wudu', say: 'Bismillah' (In the name of Allah). If one omits the Tasmiya (saying 'Bismillah') out of forgetfulness or based on an interpretation, it is sufficient for him—if Allah wills. But if he omits it intentionally, or forgets it throughout his entire ablution, then remembers it while in the middle of his wudu', he must repeat the wudu' so as to complete the merit of the ablution."
172 - Ishaq narrated to us, he said: 'Abdah ibn Sulayman narrated to us, he said: Haritha ibn Abi al-Rijal narrated to us, from 'Amrah, from 'A'ishah—may Allah be pleased with her—who said: Whenever the Messenger of Allah (peace and blessings of Allah be upon him) performed wudu' and placed his hand into the vessel, he would mention the name of Allah, and he would perform wudu' and perfect the ablution.
173 - Muhammad ibn al-Wazir narrated to us, he said: Marwan ibn Muhammad narrated to us, he said: Jarir narrated to us, from Layth, from Makhul, who said: "Whoever performs wudu' and does not mention the name of Allah, he has only cleansed the areas of ablution; and whoever performs wudu' and mentions the name of Allah, it is as if he has performed ghusl (full bath)."
• And I heard Ishaq say on another occasion: "The Sunnah of the Prophet (peace and blessings of Allah be upon him) is established that whenever he placed his hand into the water for wudu', he would say: 'Bismillah'."
Abu Ya'qub said: "When you perform wudu', say: 'Bismillah' when you begin your wudu'. And if you are performing istinja' with water, then when you begin, you mention the name of Allah." He said: "And it is more pleasing to me that he does that when he begins by washing the palms of his hands."