[3][4] He is considered the leading specialist in fiqh, usul al-fiqh, hadith, usul al-hadith, tafsir, ulum al-Qur'an (Qur'anic sciences), Qu'ranic recitation, grammar, linguistic, rhetoric, philology, history, literature, genealogy, kalam (Islamic theology), logic and Sufism.
[10]: 29 Zakariyya al-Ansari held a number of teaching positions, where he taught in Cairo for eighty years,[12] during which he moved between different schools over his long career, educating in the different Islamic sciences.
[13] He originally refused this post until Sultan Qaitbay insisted to accept his request, and the dignitaries of the state came to him seeking his approval.
[5][14] He proceeded with his work with complete integrity and apparent chastity, and he was not afraid encourage good and forbid evil, and he often burdened the advice of Sultan Qaitbay, He continued in this position for twenty years throughout the reign of Sultan Qaitbay, which is a remarkable phenomenon in his era, as it is considered a very long period for other judges.
This is because he used to rebuke al-Ghawri for injustice a lot, and the words were heavy on him, but it did not take long until he returned to the judiciary after the strong insistence of the princes, and he continued in it for five months, then he isolated himself when he felt that he was unable to carry out the burdens of the judiciary, due to his old age, His eyesight weakened, and his body atrophied, and this was in the same year (906 AH).
"[22] Najm al-Din al-Ghazzi said : “The Imam, the Sheikh of the Sheikhs of Islam, the sign of the investigators, the understanding of the verifiers, the tongue of the theologians, the Imam of the jurists and the hadith scholars, the memorizer who is specific to the height of the chains of narrators, and the attachment of the descendants to the ancestors, the scholar, the worker, the complete guardian, the one who combines the law and the truth, and the traveller to God.” Come, I uphold the paths of the way, our Lord and Master, the Chief of Judges, one of the swords of truth.”[16] The topics of Zakaria al-Ansari's writings varied greatly, as he did not leave an art from the arts of Sharia, its instruments, and other various sciences that were taught in his era, such as medicine, engineering, astronomy, arithmetic, geometry and others, except that he classified them.
In the classification, he followed the path of the scholars of his time, as it was most of them in that era to abbreviate the books of the predecessors in the form of texts to make it easier for students of knowledge to memorize them, or explain the abbreviated texts to clarify their meanings and remove ambiguity and ambiguity from their expression and manifestation, or put footnotes, which are notes and comments on explanations or fatwa books.
[5] The Indian scholar and researcher, Abdul Qadir al-Aidarous said: “And he wrote in many sciences, such as jurisprudence, interpretation, hadith, grammar, language, morphology, meanings, statement, beautiful, logic, and medicine, and he has a long tradition in Sufism, and he wrote in duties, arithmetic, algebra, interview, form, geometry, etc.