The Name 'Al Ilaah' is found in the Qur'aan.
Example from the Qur'aan:
2:163
The Name Al-Ilaah The One who deserves to be
worshipped is found in the Qur’aan in many places.
وَإِلَٰهُكُمْ
إِلَٰهٌ وَاحِدٌ ۖ لَّا إِلَٰهَ إِلَّا هُوَ الرَّحْمَٰنُ الرَّحِيمُ
“And your Ilah (God) is One Ilah (God - Allah), La ilaha
illa Huwa (there is none who has the right to be worshipped but He), the Most
Beneficent, the Most Merciful.”
[Sooratul Baqarah 2:163]
اتَّخَذُوا
أَحْبَارَهُمْ وَرُهْبَانَهُمْ أَرْبَابًا مِّن دُونِ اللَّهِ وَالْمَسِيحَ ابْنَ
مَرْيَمَ وَمَا أُمِرُوا إِلَّا لِيَعْبُدُوا إِلَٰهًا وَاحِدًا ۖ لَّا إِلَٰهَ
إِلَّا هُوَ ۚ سُبْحَانَهُ عَمَّا يُشْرِكُونَ
“…while they (Jews and Christians) were commanded [in the
Taurat (Torah) and the Injeel (Gospel)) to worship none but One Ilah (God -
Allah) La ilaha illa Huwa (none has the right to be worshipped but He).”
[Tawbah 9:31]
The word ilaah can refer to Allaah the one deserving of
worship and also to other than Allaah that is worshipped in falsehood. The word
‘Allaah’ is said to come from the word ‘ilaah’ but the word Allaah can only refer
to the One True God worthy of worship.
Points taken from ‘AbdurRazzaaq’s full version Fiqh Al-Asmaa
p86 and
An-Najdi’s book An-Nahj Al-Asnaa p52-54