Sayyiduna Abu Hurayrah (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said: "Allah has approved three things for you and disapproved three things: He is pleased with you that you worship Him alone and do not associate partners with Him, that you hold firmly to the rope of Allah and do not split into sects, and that you be sincere to the ruler; and He has disliked for you gossip (qil wa qal), excessive questioning, and wasting wealth."
Ata' bin Yazid al-Laythi says: I heard Sayyiduna Tamim al-Dari (may Allah be pleased with him) saying that the Prophet (peace and blessings be upon him) said: "The religion is sincerity (nasihah)." He (peace and blessings be upon him) said this three times. It was asked: O Messenger of Allah! To whom? He said: "To Allah, to His Book, and to the leaders of the Muslims"; or he said: "to the leaders of the Muslims and their common people."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16656
Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) says that the Prophet (peace and blessings be upon him) said: "Among (the ways of) honouring the glory of Allah are three things: honouring a grey-haired Muslim; (honouring) the bearer of the Qur'an who neither goes to extremes in it nor turns away from it; and honouring a just ruler."
Ibn al-Mubarak narrated it from Awf and made it mawquf (stopping at the Companion).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16658
Ziyad bin Kusayb al-Adawi (may Allah have mercy on him) says that Abdullah bin Amir (may Allah be pleased with him) used to deliver the sermon to the people while wearing fine (thin) clothes, with his hair combed. One day he prayed and then went in; Abu Bakrah (may Allah be pleased with him) was sitting beside the pulpit. Mirdas Abu Bilal said: Do you not see the ruler, who wears fine clothes and imitates the sinners? When Abu Bakrah (may Allah be pleased with him) heard this, he said to his son al-Usayli': Call Abu Bilal. He called him, and he said: I have heard what you said just now about the ruler. I heard the Prophet (peace and blessings be upon him) say: "Whoever honours the ruler, Allah will honour him; and whoever disgraces the ruler, Allah will disgrace him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16659
Jubayr bin Nufayr (may Allah have mercy on him) says that Sayyiduna Iyad bin Ghanm al-Ash'ari (may Allah be pleased with him) fell upon (punished) the master of Dara when it was conquered. Then Hisham bin Hakim (may Allah be pleased with him) came and said very harsh things to him. After a few nights Hisham (may Allah be pleased with him) came to apologise to him, and said to Iyad (may Allah be pleased with him): Do you not know that the Prophet (peace and blessings be upon him) said: "On the Day of Resurrection the most severe punishment will be for the one who used to punish people most severely in the world"? Iyad (may Allah be pleased with him) said: O Hisham! The one from whom you heard, those whom you saw, and those with whom you stayed, we too have met them; we have heard and we have kept company. O Hisham! Have you not heard this saying of the Prophet (peace and blessings be upon him): "Whoever has some advice for a ruler should not say it in front of everyone; let him take him by the hand and go aside with him in private. If the ruler accepts it, well and good; and if he does not, then he has fulfilled his duty"? O Hisham! You are very bold, you have dared (to speak) against the ruler appointed by Allah. Do you not fear that Allah's ruler might kill you, so that you would be slain at the hands of Allah's ruler?
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16660