Allah is the Name of the Lord, the Exalted. It is said that Allah is the Greatest Name of Allah, because it is referred to when describing Allah by the various attributes. For instance, Allah said,
[هُوَ اللَّهُ الَّذِى لاَ إِلَـهَ إِلاَّ هُوَ عَالِمُ الْغَيْبِ وَالشَّهَـدَةِ هُوَ الرَّحْمَـنُ الرَّحِيمُ - هُوَ اللَّهُ الَّذِى لاَ إِلَـهَ إِلاَّ هُوَ الْمَلِكُ الْقُدُّوسُ السَّلَـمُ الْمُؤْمِنُ الْمُهَيْمِنُ الْعَزِيزُ الْجَبَّارُ الْمُتَكَبِّرُ سُبْحَـنَ اللَّهِ عَمَّا يُشْرِكُونَ - هُوَ اللَّهُ الْخَـلِقُ الْبَارِىءُ الْمُصَوِّرُ لَهُ الاٌّسْمَآءُ الْحُسْنَى يُسَبِّحُ لَهُ مَا فِى السَّمَـوَتِ وَالاٌّرْضِ وَهُوَ الْعَزِيزُ الْحَكِيمُ ]
(He is Allah, beside Whom La ilaha illa Huwa (none has the right to be worshipped but He) the Knower of the unseen and the seen. He is the Most Gracious, the Most Merciful. He is Allah, beside Whom La ilaha illa Huwa, the King, the Holy, the One free from all defects, the Giver of security, the Watcher over His creatures, the Almighty, the Compeller, the Supreme. Glory be to Allah! (High is He) above all that they associate as partners with Him. He is Allah, the Creator, the Inventor of all things, the Bestower of forms. To Him belong the Best Names. All that is in the heavens and the earth glorify Him. And He is the Almighty, the Wise) (59:22-24).
Hence, Allah mentioned several of His Names as Attributes for His Name Allah. Similarly, Allah said,
[وَللَّهِ الأَسْمَآءُ الْحُسْنَى فَادْعُوهُ بِهَا]
(And (all) the Most Beautiful Names belong to Allah, so call on Him by them) (7:180), and,
[قُلِ ادْعُواْ اللَّهَ أَوِ ادْعُواْ الرَّحْمَـنَ أَيًّا مَّا تَدْعُواْ فَلَهُ الاٌّسْمَآءَ الْحُسْنَى]
(Say (O Muhammad :) "Invoke Allah or invoke the Most Gracious (Allah), by whatever name you invoke Him (it is the same), for to Him belong the Best Names.'') (17:110)
Also, the Two Sahihs recorded that Abu Hurayrah said that the Messenger of Allah said,
«إِنَّ للهِ تِسْعَةً وَتِسْعِينَ اسْمًا، مِائَةً إِلَا وَاحِدًا، مَنْ أَحْصَاهَا دَخَلَ الْجَنَّةَ»
(Allah has ninety-nine Names, one hundred minus one, whoever counts (and preserves) them, will enter Paradise.)
These Names were mentioned in a Hadith recorded by At-Tirmidhi and Ibn Majah, and there are several differences between these two narrations.
(Tafsir ibn Kathir)
