Sahl bin ‘Abdillah At-Tustari رحمه الله was asked: “When is it known that a man is upon the Sunnah and Jama’ah?”
He replied:
“When 10 qualities are found with him:
1) He does not abandon the Jama’ah (congregation)
2) He does not curse the Sahabah (companions) of the Prophet صلى الله عليه وسلم
3) He does not rebel against this Ummah with the sword
4) He does not reject/disbelieve in the Qadr (predestination)
5) He does not doubt in Eemaan (faith)
6) He does not argue (for the sake of argumentation) in the (affairs of the) religion
7) He does not abandon the Salah (Janazah- Funeral prayer) over those who died from the People of the Qiblah (the Muslims)
8) He does not make Takfeer (excommunicate) the people of the Qiblah before of sins
9) He does not abandon wiping over the socks
10) He does not abandon the congregational prayers behind the ruler, regardless if he is oppressive or just.”