Praise be to Allah.
Firstly: One of the things that is liked in giving names is to choose a name that indicates servitude to Allaah i.e., ‘Abd [slave] plus one of the names of Allaah, whether that is ‘Abd-Allaah [slave of Allaah] or the word ‘Abd plus any of the beautiful names of Allaah. The most beloved of such names to Allaah are the names ‘Abd-Allaah and ‘Abd al-Rahmaan (slave of the Most Merciful].
Secondly: It is haraam to give such names that indicate servitude to anyone or anything other than Allaah, such as ‘Abd al-Rasool [slave of the Messenger] or ‘Abd al-Nabi (slave of the Prophet] and so on. See also the answer to question no. 7180.
Thirdly: al-Ilaah in Arabic means “the One Who is worshipped” or “the One Who deserves to be adored and worshipped”. The idols were called aalihah (gods) because the mushrikeen worshipped them instead of Allaah, and claimed that they were deserving of that. See Ishtiqaaq Asma’ Allaah by Abu’l-Qaasim al-Zujaaji, p. 30; Lisaan al-‘Arab, entry for aliha. Some scholars said that the word “Allaah” is derived from the word “al-Ilaah” (the God). This is the view favoured by Ibn al-Qayyim and other scholars, and the initial alif of the word ilaah was elided.
Fourthly: is al-Ilaah one of the names of Allaah, and is it permissible to use it in a name signifying servitude to Him, or not?
The name al-Ilaah is included among the beautiful names of Allaah which are listed in some versions of the hadeeth, “Allaah has ninety-nine names…”, as we see it narrated by al-Bayhaqi in al-Asma’ wa’l-Sifaat, and by al-Haakim. But the list of names in this hadeeth is not the words of the Prophet (peace and blessings of Allaah be upon him), according to the scholars who are well-versed in hadeeth, as was mentioned by Shaykh al-Islam Ibn Taymiyah, Ibn Katheer, Ibn Hajar and other scholars. See Asma’ Allaah al-Husna by ‘Abd-Allaah ibn Saalih al-Ghusn, p. 170-173
Because the reports which list the names of Allaah are not reliable, many scholars have tried to find these names in the Qur’aan and Sunnah. Among those who included the name al-Ilaah in their lists of the beautiful names of Allaah are: Ibn Mandah, Ibn Hazm, Ibn Hajar, Ibn al-Wazeer and Ibn ‘Uthaymeen (may Allaah have mercy on them). See op. cit., 352.
Based on that, it is permissible to use the name 'Abd al-Ilah, and there is nothing wrong with that, in sha Allah. However, it seems that this name was not known in the past."
We do not find this name among the Sahaabah, based on what we see in al-Isaabah by Ibn Hajar. We do not find it among the names mentioned in biographies by various authors, such as Fahaaris al-Siyar by al-Dhahabi, Tabaqaat al-Shaafa’iyyah by Ibn al-Subki, Wafiyaat by Ibn Khalkaan, al-Tahdheeb by Ibn Hajar, and others. The first usage of this name that we have come across is ‘Abd al-Ilaah ibn ‘Ali ibn al-Husayn al-Haashimi, who was born in 1331 AH and died in 1377, as mentioned by al-Zarkali in al-A’laam. This is obviously very recent.