It was narrated that Abu Umamah said, in a marfu' Hadith:
"Adhere to righteousness and it is a blessing if you are able to do so. Know that the best of your deeds is prayer and that no one maintains his ablution except a believer." (ES)
English reference (ES): Vol. 1, Book 1, Hadith 279 (ES)
Arabic reference (ES): Book 1, Hadith 292 (ES)