Hadith: Allah has ninety-nine names – one hundred minus one – and no one memorizes them but that they will enter Paradise. He is One, and He loves odd numbers

عن أبي هريرة رضي الله عنه روايةً قال: «للهِ تسعةٌ وتسعون اسمًا، مائةً إلَّا واحدًا، لا يحفظُها أحدٌ إلَّا دخل الجنةَ، وهو وِترٌ يحبُّ الوِتر».
[صحيح] - [متفق عليه]

Abu Hurayrah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: “Allah has ninety-nine names – one hundred minus one – and no one memorizes them but that they will enter Paradise. He is One, and He loves odd numbers.”
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

Allah, the Almighty, has ninety-nine names, and no one memorizes them except that they will enter Paradise. To memorize them means to know them by heart. It is also said to mean believing in them, acting upon them, and showing obedience according to each name of them. This Hadīth establishes those names, yet it does not negate other, additional names. Rather, these names were specifically included because they are the most known and the clearest in meaning. This is similar to someone saying: “Zayd has one hundred dirhams which he has allocated for charity.” This does not mean that he has no other dirhams; rather, it denotes the amount of money that he has devoted to this purpose. This explanation is supported by a Hadīth which was reported by Ibn Mas‘ūd (may Allah be pleased with him) and in which the Prophet (may Allah's peace and blessings be upon him) said: “I ask You by every Name belonging to You which You have named Yourself with, revealed in Your Book, taught to any of Your creation, or preserved in the knowledge of the Unseen with You.” This Hadīth points out that Allah, the Almighty, has names that He did not reveal in His book and kept concealed from His creation. "He is One", meaning: Allah is One and has no partner. "And He loves odd numbers", meaning: He prefers odd numbers in many good deeds and acts of worship. For example, the obligatory prayers are five, the circumambulation of the Ka‘bah consists of seven rounds, the heavens are seven, the earths are seven, and many acts ought to be done three times.