Musnad Ahmad 30:384

Yazid narrated to us, Muhammad informed us, from Abu al-Zinad, from al-A'raj, from Abu Hurairah, who said: The Messenger of Allah, may Allah bless him and grant him peace, said: "Indeed, Allah has ninety-nine names, one hundred minus one. Whoever enumerates them will enter Paradise. He is Witr (Odd/One) and He loves the Witr."