It is narrated from Sayyiduna Abu Sabrah al-Ansari (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "There is no prayer without ablution, and there is no ablution for one who does not mention the name of Allah over it; and whoever does not believe in me has not believed in Allah, and whoever does not recognise the right of the Ansar has not believed in me."
Hadith Referenceالمعجم الكبير للطبراني / مسند من يعرف بالكنى / 18959