Reference: Siyar A'laam an-Nubalaa v8 p540
said:
Ishaaq al-Fazaaree - a man of Sunnah - was the one who disciplined the people of ath-Thughar and taught them the Sunnah. And if an innovator entered ath-Thughar, he would oust him [to protect the people of ath-Thughar from his innovation].
