The practical model of rooting that Al-Mahdi established in his jurisprudence. In order to support and convince others of it, he had to provide a theoretical explanation of the reality of the origin, its rulings, its relationship to the branch, and the methods of its proof. This is what he actually did in his book "A'azz ma Yutlab" (The Most Sought-After), and we will present his views on this matter below.

The Origin and its Rulings: Al-Mahdi discussed the origin and its rulings in detail. He dedicated a special chapter to this in his book "A'azz ma Yutlab." He prefaced it with a summary of the issues he discussed, saying: "As for the origin, fourteen chapters are related to it: one is its knowledge and reality, the second is the way to prove it, the third is whether it is limited or not, the fourth is the evidence for its limitation, the fifth is the knowledge of the branch, the sixth is its proof, the seventh is its limitation, the eighth is the evidence for its limitation, the ninth is the impossibility of proving a branch without an origin, the tenth is the impossibility of proving an origin without a branch, the eleventh is the connection of knowing the branch to knowing the origin and the connection of knowing the origin to knowing the branch and the interdependence between them in knowing all of them by knowing one of them, the twelfth is the impossibility of proving one branch from two contradictory origins, the thirteenth is the impossibility of proving one origin for two contradictory branches, and the fourteenth is the difference between the origin and the sign." We will try to...

The reality of the origin and its limitation: Have you not seen how the origin of a tree is that upon which it is established and from which its branches sprout, as Allah Almighty mentioned in His Book when He said: "The parable of a good word is like a good tree, its roots firm and its branches in the sky" (Ibrahim/24). The origin is only an origin in relation to its branch, and the branch is only a branch in relation to its origin. They are two interdependent matters.

See the same source: Ibn Tumert. See the explanation of "A'azz ma Yutlab." The unknown.