If you see a man making du'a for the ruler, know that he is a follower of the Sunnah

Question:
This questioner says: Some of the Tabi'un (the generation after the Companions) said, "If you see a man making du'a for the one in authority, know that he is a follower of the Sunnah. And if you see him not making du'a for the one in authority, know that he is a follower of bid'ah (religious innovation)." Is this in the Friday sermon? And how do we know a follower of bid'ah?

Answer:
Yes. This is because the sects appeared in the time of the Salaf (the earliest generations), and the Khawarij and the Mu'tazilah (a rationalist theological sect) emerged, who break the bond of obedience and separate from the community.
So one of the signs of these people is that they do not make du'a for the rulers. Their not making du'a for the rulers is evidence that they adhere to the doctrine of the Khawarij or that they approve of it, because making du'a for the rulers is making du'a for the Muslims. If the rulers are righteous, the Muslims are righteous, and if they are corrupt, the Muslims are corrupt. So the one who makes du'a for the rulers is, in reality, making du'a for the well-being of Islam and the Muslims. This is done in the Friday sermon, and in every du'a in which the Muslim makes du'a, he makes du'a for the rulers. Yes.