The grandmother of Rabah bin Abd al-Rahman bin Abi Sufyan bin Huwaytib narrated from her father (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "There is no prayer for the one who has not performed ablution, and there is no ablution for the one who has not said 'Bismillah' (in the name of Allah); and whoever does not love the Ansar does not believe in me either."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 194