Abdullah bin Burayda bin al-Husayb عبد الله بن بريدة بن الحصيب الأسلمي · The Book of al-Bay'ah

'No prophet has eve been sent, nor has there been any Khalifah after him, but he has two groups of advisers, a group that tells him to do good and a group that tells him to do evil. Whoever is protected from the evil group, then he is indeed protected.