Regarding ibn Taymiyya’s conduct with his opponents during debate, on page 326 and 327 of his book Dhaylu Tareekhil Islam, Al Imam Adh Dhahabi (D. 748AH) said:
مع اننى لا اعتقد فيه العصمة كلا فانه مع سعة علمه و فرط شجاعته و سيلان ذهنه و تعظيمه لحرمات الدين بشر من البشر تعتريه حدة فى البحث و غضب وشظف للخصم يزرع له عداوة فى النفوس و نفورا عنه وإلا والله لو لاطف الخصوم و رفق بهم ولزم المجاملة و حسن المكالمة لكان كلمة اجماع
“…although I do not believe him to be infallible (ma’soom). Most definitely not! Because despite his vast knowledge, extreme courage, overflowing intellect, and reverence for the sanctities of the religion, he was but a man. During debates he would be overcome with harshness, hot temper, and toughness with his opponents which would plant in the souls the seeds of enmity, aversion, and dislike for him. Otherwise, had he been polite and kind with his opponents and observed etiquette and a graceful mode of speech, he would have been a word of consensus.”
Courtesy of Shaykh Abdur Rahman Sondalaani:
The Reality of ibn Taymiyya 