For the sign, in that it is what the ruling is established by, not by it. Establishing with something implies causality that necessitates obligation. Establishing at something implies absolute conjunction that implies only existence. As for the principle with Al-Mahdi, it corresponds with Al-Bazdawi to the cause that necessitates the ruling. This is because the principle with the former is the divine address that necessitates rulings. And the causes with the latter are not necessitating in themselves; rather, the one who necessitates rulings is Allah, the Almighty. But His necessitating them was hidden, so the obligation was attributed to the causes, making them necessitating in the eyes of the servants by the maker of the law. And it is fitting to point out that what the law called them as such. Al-Bazdawi called it a sign of the ruling. And his commentator, Ala' al-Din al-Bukhari (d. 730 AH/1329 AD), explained the principles as a sign. This is not applicable to the sign that Al-Mahdi spoke of, despite the similarity in name, but rather it is a lesser degree than it in terms of its entry into its obligation or its existence. Al-Ghazali spoke in Al-Mustasfa about what Al-Mahdi called a sign in the chapter he dedicated to the reasons for the ruling. He defined the reason as "an expression of what the ruling is established by, not by it." This definition is the same as the one by which Al-Mahdi defined the sign. Al-Ghazali included within the concept of reason, in this sense, as an example, the sun's setting in relation to prayer, and the sighting of the moon in relation to fasting. We have seen that Al-Mahdi considered these to be among the signs of the ruling of prayer and fasting. He also included within the reason the legal causes and considered them signs for revealing the ruling, saying: "This is good for legal causes because they do not necessitate the ruling in themselves but by the necessitating of Allah Almighty." And for His appointment of these reasons as signs to reveal the ruling. So, legal causes are, in meaning, revealing signs. Thus, what the ruling is established by. This generalization by Al-Ghazali of the reason to include the legal cause has a parallel in the generalization of legal causes, as stated in the same source. But what is consistent with the concept of the sign according to Ibn Tumart.