Asmaul Husna, Allahs 99 Names and Attributes, Names of God in Islam, Narrated Abu Huraira:
Allah's Messenger (ﷺ) said, "Allah has ninety-nine Names, one-hundred less one; and he who memorized them all by heart will enter Paradise." To count something means to know it by heart.
Reference : Sahih al-Bukhari 7392
In-book reference : Book 97, Hadith 21