It is necessary that Allah would have Power over everything. What is meant by “everything” here is the mental possibility. Thus, the mental impossibility is excluded from that, because it does not accept existence, so it is not suitable to be related to the Power of Allah.
Ibn Hazm opposed that. He said, “Allah the Mighty and Great has the power to take a child for Himself. If He did not have the power to do it He would be weak.” However, what he said is not necessary, because taking a child for Himself is impossible to be attributed to Allah. The mentally impossible is not a subject of the Power.
Power not being related to something could be because of deficiency, and that is in reference to the creation, and sometimes it would be because that thing does not accept entrance into existence, meaning to occur, because it is mentally impossible, or because it does not accept non-existence because of it being mentally necessary. The inability is the first one, which is negated from the Power of Allah the Exalted; not the second one, it is neither permissible to say that Allah has power over that, nor that He is weak. Some said, “Just like you do not say about the stone [that it is] knowledgeable or ignorant.”
Likewise is the response to the saying of some atheists, “Is Allah able to create one like Himself?” In that there is deeming permissible that which is mentally impossible. The clarification for that is that Allah is Eternal, and had He had a similar it would have been eternal, and the eternal would not be created because it is already existent. So how would the existing thing be created?
As for the mentally impossible, its non-acceptance of entering into existence is clear. As for the mental necessity, it does not accept an eventual existence because its existence is eternal. There is a difference between existence and entering into existence. Existence includes the eternal existence and the eventual existence; both are called existence. As for entering into existence, that is the eventual existence.
The mental necessity refers to Allah and His Attributes. Allah’s Existence is a mental necessity. His Existence is Eternal and His Attributes are Eternal. It is not said about Allah or His Attributes that they came into existence, because the Existence of Allah and His Attributes is Eternal. When we said, “The mental necessity does not accept entry into existence,” that is correct. However, the understanding of some of the beginners in the Creed is deficient in this. As for the one who is experienced in that, the intended meaning is clear.
 In reference to existence.