Speaking the truth before rulers

Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says: "Soon there will be rulers over you who will abandon this much of the Sunnah. If you let it go, they will make it like this; and if you let it go, they will bring an even greater calamity."
This narration has been recorded by Imam al-Tabarani, and its narrators are thiqat (trustworthy).

Sayyiduna Umar al-Laythi (may Allah be pleased with him) narrates: There was a question on my mind which had saddened me, because I had not asked the Prophet (peace and blessings be upon him) about it, nor had I heard anyone asking the Prophet (peace and blessings be upon him) about it. I was looking for a suitable opportunity. One day I came to him (peace and blessings be upon him) while he was performing ablution. I found him in a situation, in two respects, that I had wished to find him in: I found that he was free and in a pleasant mood. I said: "O Messenger of Allah! Permit me to ask you a question." The Prophet (peace and blessings be upon him) said: "Ask whatever seems fit to you!" I said: "O Messenger of Allah! What is faith (iman)?" The Prophet said: "Patience and gentleness." I asked: "Among the believers, who is most excellent in faith?" He (peace and blessings be upon him) said: "The one whose character is best." I asked: "Among the Muslims, who is most excellent in Islam?" He (peace and blessings be upon him) said: "The one from whose hand and tongue people are safe." I asked: "Which jihad is most excellent?" He lowered his head and remained silent for quite a while, until I feared that perhaps I had displeased him (peace and blessings be upon him), and I wished that I had not asked him, for before that I had heard him (peace and blessings be upon him) saying: "The greatest sinner among the Muslims is the one who asks about something that was not forbidden to them, and because of his asking that thing becomes forbidden." So I said: "I seek refuge in Allah from the wrath of Allah Almighty and the wrath of His Messenger (peace and blessings be upon him)." Then the Prophet raised his head and said: "What did you say?" I said: "Which jihad is most excellent?" The Prophet said: "Speaking a word of justice (that is, truth) before an oppressive ruler."
This narration has been recorded by Imam al-Tabarani. Its chain contains one narrator, Bakr bin Khunays, and he is da'if (weak). (Allamah al-Haythami says:) I say: some hadiths of this kind will come in the chapter on trials (fitan), in the chapter on condemning wrongdoing, if Allah wills.

Sayyiduna Abu Hurayrah (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "O Abu Hurayrah! Do not go to the rulers; and if you are ever compelled to, then do not go beyond my Sunnah, and do not fear their sword and their whip in commanding them to have taqwa (fear) of Allah."
This narration has been recorded by Imam al-Tabarani in al-Mu'jam al-Awsat. Its chain contains one narrator, Abd al-Rahman bin Zayd bin Aslam, and he is da'if (weak).

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) said: "Whoever is present with a ruler should say something good or else remain silent."
This narration has been recorded by Imam al-Tabarani in al-Mu'jam al-Awsat. Its chain contains one narrator, Salih bin Muhammad bin Ziyad, whom Imam Ahmad and others declared thiqah (trustworthy), while a group declared him da'if (weak); its remaining narrators are the narrators of the Sahih.