Sa'id b. Zaid reported God’s messenger as saying, "He who does not mention God’s name while performing ablution is not credited with having performed it.”
Tirmidhi and Ibn Majah transmitted it. Ahmad and Abu Dawud transmitted it from Abu Huraira, and Darimi from Abu Sa'id al-Khudri from his father, and they added at the beginning,
“He who has not performed ablution is not credited with observing prayer”.