All praise is due to Allah, and may peace and blessings be upon the Messenger of Allah. To proceed:
It is not correct to call Allah Almighty “Al-Mujir” as one of His Most Beautiful Names, because the Names of Allah are established only through revelation, and neither the Qur’an nor the authentic Sunnah establishes this as a Name of Allah.
The Most Beautiful Names of Allah cannot be established merely through reason or personal deduction. Rather, there must be evidence from revelation. Allah Almighty is only named by what He has named Himself or what His Messenger ﷺ has named Him.
Allah Almighty says:
“And do not pursue that of which you have no knowledge. Indeed, the hearing, the sight, and the heart—about all of those one will be questioned.”
[Al-Isra’ 17:36]
And He says:
“Say: My Lord has only forbidden immoralities—what is apparent of them and what is concealed—and sin, and oppression without right, and that you associate with Allah that for which He has sent down no authority, and that you say about Allah what you do not know.”
[Al-A‘raf 7:33]
For this reason, Ahl al-Sunnah have established that the Names of Allah are based solely on revelation; nothing may be added to or removed from them without evidence.
Allah Almighty says in the Qur’an:
“Say: In whose hand is the dominion of all things, and He grants protection while none can grant protection against Him, if you know?”
[Al-Mu’minun 23:88]
Some later scholars, including al-Sharbasi, cited this verse as evidence that “Al-Mujir” is one of the Most Beautiful Names of Allah.
However, it is not correct to turn the verb mentioned in the verse into a Name of Allah merely by deriving a noun from it, because the verse informs us about an action of Allah: He grants protection to His servants. It does not explicitly name Allah “Al-Mujir.”
Here, the important distinction between the category of Names, the category of Attributes, and the category of statements made about Allah becomes clear.
The category of Names is narrower than that of Attributes, and the category of Attributes is narrower than that of statements or descriptions made about Allah.
An action or attribute may be established for Allah without it being permissible to derive from it a Name that has not been established by revelation.
For example, it is established that Allah loves, is pleased, and becomes angry. We therefore affirm the attributes of love, pleasure, and anger as they occur in the revealed texts. However, we do not derive from these verbs Names such as “the Lover,” “the Angry,” or “the Pleased” and regard them as Most Beautiful Names unless there is evidence establishing them as such.
Likewise, speech, will, and rising over the Throne are established for Allah. We affirm these attributes, but this does not necessarily mean that we name Him “the Speaker,” “the Willer,” or “the One who rises over the Throne.”
As for statements made about Allah, this category is broader than the categories of Names and Attributes. Allah may be referred to using expressions whose meanings are correct even though they are not established as Most Beautiful Names or formally established Attributes.
For this reason, Ibn Taymiyyah, may Allah have mercy on him, explained that the scope of statements made about Allah is broader than that of invoking Him; Allah is invoked only by His Most Beautiful Names, whereas one may speak about Him using expressions with correct meanings even if they have not been established as Names of His.
Because the mere occurrence of a verb in a revealed text is not sufficient to establish a Name derived from it.
The verse establishes that Allah Almighty grants protection to whomever He wills. This reflects the perfection of His power, sovereignty, mercy, and protection of His servants. However, it does not necessarily follow that “Al-Mujir” is one of His Most Beautiful Names.
This is an important point of precision concerning the Names and Attributes of Allah: Not everything that may correctly be affirmed as a description of Allah or stated about Him may necessarily be made into a Name of His.
As far as we know, “Al-Mujir” is not established as one of the Most Beautiful Names of Allah, because there is no authentic and explicit evidence naming Allah Almighty by this Name. What occurs in the Qur’an is His statement: “He grants protection while none can grant protection against Him.” This informs us about His action and is not an explicit text establishing “Al-Mujir” as a Name.
The principle is that the category of Names is more specific than that of Attributes, and the category of Attributes is more specific than that of statements made about Allah. Therefore, Names of Allah may not be derived merely from His actions without evidence from revelation.
And Allah knows best.