Narrated Abu Hurairah: The Messenger of Allah ﷺ said: The prayer of a person who does not perform ablution is not valid, and the ablution of a person who does not mention the name of Allah (in the beginning) is not valid.
Hadith Referenceسنن ابي داود / كتاب الطهارة / 101
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:حسن, مشكوة المصابيح (403), وللحديث شواهد منها ما أخرجه ابن ماجه (397) وسنده حسن
Explaining the tradition of the Prophet ﷺ that the ablution of a person who does not mention the name of Allah is valid, Rabiah said: This tradition means that if a person performs ablution and takes a bath but does not have the intention to perform ablution for prayer and purify himself from sexual defilement, his ablution or bath is not valid.
Hadith Referenceسنن ابي داود / كتاب الطهارة / 102
Hadith Gradingالألبانی:صحيح مقطوع | زبیر علی زئی:ضعيف, إسناده ضعيف, عبد اللّٰه بن وهب المصري مدلس (طبقات ابن سعد: 518/7،الفتح المبين: ص 25) و عنعن, انوار الصحيفه، صفحه نمبر 16
Hadith Takhrij« تفرد به أبو داود، (تحفة الأشراف: 18635) (صحیح) »