The Tanya often mentions the following quote from the Zohar which literally reads, “He and His bones are One.” Reformulated idiomatically the quote means, "He and His attributes are One.”; i.e. that the Creator is One with His attributes.
As I explained in previous writings, the Creator's Oneness and Infinity are really the same thing. Saying the Creator is One is the same as saying that He’s Infinite. Vice versa, saying that He’s Infinite is the same as saying that He’s One.
Briefly reviewed: His Oneness is so pure that it's seamless, meaning no parts. The logical underpinning of this concept is that since He’s the ultimate of perfection His Oneness too must be perfect. A Oneness is only perfect if devoid of its opposite, namely multiplicity.
Moving on to demonstrate His Infinity, a partless Being has no beginning, middle or end; as these too are parts. The result is that His Oneness equals His Infinity.
Though there's no difference between His Oneness and Infinity, it is my understanding that inside of the created realms, spiritual and earthly, His Oneness becomes the origin for what is cosmically female and His Infinity becomes the origin for what is cosmically male. This is a lot like the phenomenon of thunder and lightening. Both are the same event, an electric disturbance in storm clouds. Yet, it this one event have two separate experiential manifestations; one for the eyes and the other for the ears, i.e. lightening and thunder. So too, what’s identical in the Ultimate Source, the Creator, can manifest separately - as the cohesive tendencies of cosmic female and the expansive tendencies of cosmic male.
So how are His attributes One with Him? Here I am discussing an answer which is on a different level than the Tanya’s answer. The Tanya's answer mostly addresses the dynamics of O'lam Atzilus (the World of Emanations). I am working with how the concept is also true in the Oneness/Infinity of His Being as well.
The nature of children is that their traits fall somewhere on the spectrum between their parents’ genes. In fact, in a sense, one can say that this is what it means to be a child of two parents - i.e. a human being who’s genetically in between two parents.
All the Creator's attributes are caused by some interplay between cosmic male and female. So quite literally all these attributes have "parents". Differences in the influence between cosmic female and male will make one attribute different from the next. For example, there's more cosmic male influence in the attribute of divine supervision and more cosmic female influence in the attribute of hearing prayer. This is not surprising, as human children who share the same set of parents also tend to have a variety of tendencies; some tending more towards one parent than to the other.
Just as cosmic male and female have their origin in His Infinity/Oneness, so too the origins everything which will emerge from the union of cosmic female and male also have their origins there too, as existing between Infinity and Oneness. Since in this kind of pure existence Oneness and Infinity are identical, therefore, everything between Oneness and Infinity are identical too. Hence, in that ultimate core state of origin, He and His attributes are indeed One!
In Kabbalah’s famous “Tree of Life” diagram, the right column is cosmically male. The left column is cosmically female. Then there’s a middle column which is the “child” of the right and left columns. It’s between the polarized extremes of cosmic male and female; a middle path between them. Clearly, all three columns of the Tree are manifestations of what’s seamlessly identical the coreness of Ultimate Being; Oneness, Infinity and all in between.