He is the jurist and renowned historian and a descendent of Umar bin Al Khattab (رضي الله عنه), Abu Al-Abbas Shihab Al-Din Ahmed bin Fadlallah bin Yahya bin Ahmed Al-Umari (700 – 749AH).
One of his sheikhs was Taqi ad Din Ibn Taymiyya (d. 728H) and he had penned down a biography of Ibn Taymiyya in Vol 5 of his popular encyclopedic work Masalik al-abṣar fi mamalik al-amsar. Being a direct student, it is fair to say that Ibn Fadlallah can be considered a reliable biographer of Ibn Taymiyya. There are no reports of criticism against Ibn Fadlallah’s character and scholarship nor any reports of conflict with Ibn Taymiyya that would warrant any doubts of bias against Ibn Taymiyya.
On the contrary, Ibn Fadlallah spent several pages of his book pouring lavish praises upon Ibn Taymiyya, starting off with calling him the “the Allamah”, “the Hujjat”, “the Mujtahid”, “sheikh al Islam”, “the ocean”, “the full moon” and so on; exhibiting his impartial and unprejudiced nature in this case.
That being the case, he also left us with some critical evaluation of Ibn Taymiyya, which we see below:
https://al-maktaba.org/book/11790/1575
Roughly translated:
However, in accordance with what was predestined he fell into faulting on certain matters, and he made mistakes which anyone who speaks on a lot of issues are not free from. And I think – may Allah forgive him – that he received the repercussion/retaliation of it in this world itself, and he took the share of its afflictions in general and in particular. This is due to his disparagement of some of the ulema who preceded him, and his untying/dissolution of many of the rules/foundations laid by the great scholars of the past, and his backing away from showing reverence to the elders, and his takfir against many of the fuqara (i.e. sufis),
https://al-maktaba.org/book/11790/1576
Continue:
and his falsifying of most of the opinions (of the scholars), and tried to bring the ignorant common folk and people of disputation closer to himself, and in the end he gave fatwa on the matter of ziyarat and divorce, and then he publicized it until people with no religion and morals started to speak of it. So he got overpowered and consumed by his enemies, and released the hands of enemies against him, and assisted in feeding their fire, …..and until he died his honor was plundered and his qualities shattered and its remains could not be assembled, perhaps this was a goodness intended for him (by predestination), …. however this was due to him intentionally creating discord, and in following a path other than that of the predecessors, and his strengthening of weak masaail, ….. , and that caused him to be alienated from his homelands, and him getting pierced by arrows of the tongue, and him handing over spears to everyone who wanted to beat him. For this reason he continued to be grieved throughout his life. …….
And then Ibn Fadlallah continues along going back to generously praising Ibn Taymiyya and relating other information on his life and work.
For more, one can also see Ibn Fadlallah’s entry on Sheikh al Islam Taqi al-Din al-Subki (683-756 AH) praising him for staunchly clearing up controversies created by Ibn Taymiyya: https://al-maktaba.org/book/11790/1624
What is important here is that the qualities which were criticized by Ibn Fadlallah are the characteristics that modern day pseudo salafis take from Ibn Taymiyya whereas none of his praiseworthy qualities can be found among pseudo salafis. If there is a matter in which Ibn Taymiyya differed from the ijma or vast majority of scholarship then they they consider Ibn Taymiyya to have the final say on it and impose it on the Muslim world and label those who disagree as unbelievers & heretics. And if there is a matter in which even Ibn Taymiyya agrees with the vast majority of Islamic scholarship and goes against the views propagated by pseudo salafism today then they swiftly abandon Ibn Taymiyya as “only a human who is not free from error” and continue their campaign of dividing and fighting Muslims.
Wahhabism Unveiled 