Ibn Katheer said, "And the least he would do when he heard something was to memorise it and then engage himself in learning it.he was intelligent and had committed much to memory. He became an imaam in tafseer and everything related to it. He was also knowledgeable in fiqh. And it was said that he was more knowledgeable of the fiqh of the madhhabs than the followers of those very same madhhabs, (both) in his time and other than his time. He was a scholar of the fundamental issues (usool), the subsidiary issues (furoo'), of grammar, language and other textual and intellectual sciences. And no scholar of a science would speak to him except that he thought that the science was the speciality of Ibn Taymiyyah. As for hadeeth, then he was the carrier of its flag, a haafidh, able to distinguish the weak from the strong and fully acquainted with the narrators."
Thus, the issue of the personality of Shaikh ul-Islaam, the reality of his following in the footsteps of the Salaf and of his noble character, is one of clearing the injustices of the unjust, the deception of the deceivers and the foolishness of the foolish - and this is by narrating what has been said about him by the people of knowledge in order give a more realistic portrayal of his personality.
Shaikh Saleem al-Hilaalee continued, "And he (al-Haafidh adh-Dhahabee in 'Tadhkirat ul-Huffaadh') said, 'And he was amongst the oceans of knowledge, from the limited intellectuals, the ascetics, the unique individuals, the great braves, the most generous nobles. He was praised by both the one who agreed with him and the one who differed with him and he became famous by his works, and perhaps they number three-hundred volumes'. And he also said, 'He held certain rulings which were unique to him and on account of which his honour was attacked. But these are obscured by the (vast) ocean of his knowledge, for Allaah the Most High, has pardoned him and is pleased with him. I have not seen the likes of him, and the word's of every person from this ummah can be accepted or rejected, so what was he?'
And al-Haafidh adh-Dhahabee said in 'al-'Ibar fee Khibar min 'Ibar' (4/84), "And Shaikh ul-Islaam, Taqee ud-Deen, Ahmad bin 'Abdul-Haleem died in the prison of Damascus on the 22nd night of Dhul-Qa'dah... and he excelled in tafseer, hadeeth, ikhtilaaf (the issues in which there is difference of opinion) and the principle affairs (of the religion). He used to display (remarkable) intelligence and his works number more than two-hundred volumes. He also had some strange opinions on account of which his honour was attacked, and he was a leader in generosity, braveness, and was content with little. His disciples numbered more than 50,000 and he was at the forefront, may Allaah have mercy upon him."
And he (al-Haafidh adh-Dhahabee) said in 'Mu'jam ash-Shuyookh' (1/56-57), "Ahmad bin 'Abdul-Haleem bin 'Abdus-Salaam bin 'Abdullaah bin Abul-Qaasim bin Taymiyyah, our Shaikh, the Imaam, Taqee ud-Deen Abul-'Abbaas al-Harraanee, the matchless individual of the time with respect to knowledge, cognizance, intelligence, memorisation, generosity, asceticism, excessive braveness and abundancy of (written) works. May Allaah rectify and direct him. And we, by the praise of Allaah, are not amongst those who exaggerate about him and nor are we of those who are harsh and rough with him. No one with perfection like that of the Imaams of the Taabi'een and their Successors has been seen and I did not see him (Ibn Taymiyyah) except engrossed in a book."
And he (al-Haafidh adh-Dhahabee) said, "And his followers consisted of nations, (the like of) their number could not be found at the graves of the Soofees, and he did not leave behind him anyone similar to him in knowledge, or even one who approached him in it."
And he said in 'Mu'jam al-Muhadditheen' (p.25), "Ahmad bin 'Abdul-Haleem... the Imaam, the Scholar, the Haafidh, the Hujjah (the decisive proof), the unique individual of the era, ocean of sciences, Taqee ud-Deen Abul-'Abbaas al-Harraanee, then Dimashqee."