Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Whoever performs ablution and mentions the name of Allah, his whole body becomes purified; and whoever performs ablution and does not mention the name of Allah, only the places of ablution become purified."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 200