It is narrated from Rabah bin Abdur Rahman (may Allah have mercy on him) that his grandmother heard from her father (Sayyiduna Sa'id bin Zaid, may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The prayer of a person who does not have ablution is not accepted, and the ablution of a person who does not recite «بِسْمِاللّٰہِ» over it is not accepted, and whoever does not believe in me (Muhammad, peace and blessings be upon him) will not be able to believe in Allah Almighty, and the servant who does not love the Ansar will not be able to believe in me."
Hadith Takhrij«اسناده ضعيف، لضعف ابي ثفال المري۔ أخرجه مختصرا الترمذي: 25، وابن ماجه: 398 ، (انظر مسند أحمد ترقيم الرسالة: 23236 ترقیم بيت الأفكار الدولية: 23624»
Brief Explanation
Benefits: … It is also narrated from Sayyiduna Anas radi Allahu anhu that the Messenger of Allah sallallahu alayhi wa sallam said to the Companions: ((Perform ablution (wudu) with “Bismillah.”)) … Perform ablution by reciting “Bismillah.” (Nasa’i: 78) From these ahadith, it is understood that reciting “Bismillah” at the beginning of ablution is necessary, and only the words “Bismillah” should be uttered, not “Bismillahir Rahmanir Rahim.”