וְאֶל־מִ֥י תְדַמְּי֖וּנִי וְאֶשְׁוֶ֑ה יֹאמַ֖ר קָדֽוֹשׁ׃
A quem, pois, me comparareis, para que eu lhe seja semelhante? diz o Santo.
Rambam
The third principle Denial of His physicality and that is that we believe that this Unity that we mentioned is not a body and not the power of a body and that actions of a body do not relate to Him, not in His essence and not in His doings. And hence the sages, may their memory be blessed, denied [the possibility of] His composition and dissolution and said (Chagigah 15a), "Above there is no sitting or standing, no backside (aoref) and no weariness (aipui)," which is to say say no dissolution, and that is aoref, and no composition, and that is aipui, as per the usage (Isaiah 11:14), "And they aifu on the shoulder of the Philistines," which is to say they pushed themselves onto [their] shoulder to connect to them. And the prophet said (Isaiah 40:25), "'And to whom do you compare Me and I be equated,' says the Holy."[But] were He a body, He would be comparable to [other] bodies. And everything that comes in the holy Scriptures that describes Him in physical ways, such as walking or standing or sitting or speaking, or similar to it, it is all by way of metaphor. And so did the rabbis say (Berakhot 31b), "The Torah speaks in the language of people." And the sages already spoke much about this matter. And this third principle is indicated by that which is stated (Deuteronomy 4:15), "for you did not see any image" - which is to say, you did not perceive Him as something with an image, because He is - as we mentioned - not a body and not the power of a body.
Rabbeinu Bahya
A more rational approach to our line: we all know of many phenomena both above terrestrial earth and below in our world which exercise their influence on our lives in one form or another. It stands to reason that above all of these phenomena there is a hand which directs them all. The proliferation of the phenomena we witness must have its origin in a single force (compare Shaar Hayichud Chovot Halevavot chapter 5). Just like the number 1 is the first in a string of numbers, so Unity is the first (in terms of time) of a number of phenomena. Seeing that we are all witnesses to so many and different phenomena in the universe, it is quite clear that all of them must be derivatives of an original phenomenon, the Ultimate Cause. Even though the name “one” is applied to many things this description is misleading and inaccurate. It is a habit of people to use terms which, strictly speaking, apply to only one phenomenon and to describe other phenomena as possessing such characteristics. For instance, even in the Torah we find the Tabernacle referred to as אחד, “one,”(Exodus 26,6) although we all know that it was composed of many different parts. The reason the Torah described it on that occasion as “one,” was that all its constituent parts had been joined together and placed in their correct positions so that the finished product appeared to be “one.” Nonetheless the Tabernacle was subject to being dismantled and to no longer appear as a single unit.
We find that G’d told the prophet (Ezekiel 37,16) “take for yourself ‘one’ tree (or piece of wood).“ The expression אחד in that verse is a misnomer as there is only one phenomenon to which that definition can truly be applied, but the prophet describes it as such as he wants to portray a concept, i.e. the symbol of unity, something undivided. Although man is composed of 248 limbs the composite of these 248 limbs is called “one man.” Even the raw material man is made of is a composite of 4 elements; nonetheless we speak of “flesh” as if it consisted of a single raw material. All of the components of man will disintegrate at death proving that what was considered as “one” during his lifetime was in reality nothing of the kind. [Science may be defined as the search for the original single cause of the universe. Ed.]. Even amongst the celestial beings, the angels which are made of a uniform raw material and are therefore not subject to disintegration the term אחד cannot be applied in the true meaning of the word, seeing that each angel is only one of many such angels, so where is his uniqueness? The same applies to our souls. Although it is not an amalgam of elements such as our body, there are thousands of souls so how could a soul be truthfully described as אחד, truly unique? In other words, none of the phenomena in the universe can accurately be described as אחד with the exception of the Lord G’d Who is truly one of a kind in the absolute sense of the word. This is what the prophet Isaiah 40,25 meant when he said, paraphrasing G’d: ואל מי תדמיוני ואשוה, “to whom do you wish to compare Me, to whom can I be likened?”
We find that G’d told the prophet (Ezekiel 37,16) “take for yourself ‘one’ tree (or piece of wood).“ The expression אחד in that verse is a misnomer as there is only one phenomenon to which that definition can truly be applied, but the prophet describes it as such as he wants to portray a concept, i.e. the symbol of unity, something undivided. Although man is composed of 248 limbs the composite of these 248 limbs is called “one man.” Even the raw material man is made of is a composite of 4 elements; nonetheless we speak of “flesh” as if it consisted of a single raw material. All of the components of man will disintegrate at death proving that what was considered as “one” during his lifetime was in reality nothing of the kind. [Science may be defined as the search for the original single cause of the universe. Ed.]. Even amongst the celestial beings, the angels which are made of a uniform raw material and are therefore not subject to disintegration the term אחד cannot be applied in the true meaning of the word, seeing that each angel is only one of many such angels, so where is his uniqueness? The same applies to our souls. Although it is not an amalgam of elements such as our body, there are thousands of souls so how could a soul be truthfully described as אחד, truly unique? In other words, none of the phenomena in the universe can accurately be described as אחד with the exception of the Lord G’d Who is truly one of a kind in the absolute sense of the word. This is what the prophet Isaiah 40,25 meant when he said, paraphrasing G’d: ואל מי תדמיוני ואשוה, “to whom do you wish to compare Me, to whom can I be likened?”
Kli Yakar
The concept of the image and likeness is: that in all visions, it is God’s way to appear in the likeness of a human form, even though without doubt there is no actual image or likeness [to God], as it is written To whom will you compare Me that I should be equal? says the Holy One (Isaiah 40:25). And it is written: What likeness will you arrange for Him? (Isaiah 40:18). Nevertheless, when He appears, He shows the likeness of a human to His creatures, and because of the importance of humans, He appears in this likeness, as it is written And on the throne was a likeness with the appearance of a human (Ezekiel 1:26). Behold, you see that in truth there was no actual human appearance there, but rather a likeness with the appearance of a human. Similarly, He appeared at the sea as a warrior and at Mount Sinai as an elder. Therefore, it is proper to show respect to this likeness, and one who murders diminishes this likeness, because he causes God to no longer desire to appear in this likeness, since it has become despised among the creatures. And one who sees a murdered person [is reminded of the verse] for a hanging person is a curse of God, and there is no need to elaborate further on this.