The great scholar Ibn Baaz (may Allaah have mercy upon him, died 1420AH) was asked, “Is it from the methodology of the Salaf  to criticize the rulers from the pulpits? And what is the methodology of the Salaf in advising the rulers?”
So he answered:
“It is not from the methodology of the Salaf to criticize the rulers from the pulpits, because that would incite chaos, and it would involve not listening and obeying in that which is good. And this would mean becoming engrossed in that which harms and does not benefit. However, the way of advising that the Salaf followed was to write to the ruler, or to convey the advice to the Scholars who would then convey it to him, until he has been directed towards good. So opposing the evil can be done without mentioning the doer. So adultery, intoxicants and interest can be opposed without mentioning the one who is involved in them. And it is enough of an opposition to sins that they be warned against without mentioning that so and so is involved in them, whether it is the ruler, or other than the ruler.
And when the fitnah (trial, discord) occurred in the time of ʿUthmaan  , some people said to Usaamah bin Zayd , ‘Will you not speak to ʿUthmaan?’
So he said, ‘Do you think that I have not spoken to him, just because you have not heard it from me? Verily I will speak to him concerning what is between him and me, without opening an affair which I would not like to be the first to open.’ 
So when they (the Khaarijites) opened it, evil took place in the time of ʿUthmaan . They opposed ʿUthmaan openly, thus completing the tribulations, fighting and corruption, which has not ceased to affect the people to this day, was brought about. And this caused the tribulation to occur between ʿAlee and Muʿaawiyah , and ʿUthmaan was killed for these reasons…
Furthermore, a large number of Companions and others besides them were killed due to this open rebellion and the open proclamation of the faults of the ruler, until the people began to hate the one charged with authority over them and killed him. We ask Allaah for success.” 
 Salaf: Those who came before us from the earliest generations of Muslims. In the purest sense, the term refers to the Companions of the Prophet . And thus, a Salafee is a Muslim who precisely follows their way in creed, methodology and all affairs of religion.
 ʿUthmaan bin Affaan : The noble Companion of the Prophet , who married two of his daughters, after one died, the Prophet offered him the other for marriage – thus he is nicknamed “Thun-Nurayn”, (Possessor of the two Lights). He was the third Rightly Guided Caliph of Islaam. It is not permissible to criticise or attack him or his character. Sayyid Qutb famously launched severe criticisms against this Caliph as well as several other Companions of the Prophet.
 An authentic narration: Related by Ahmad (3/403) and Ibn Abee ʿAasim (2/521).
 ʿAlee bin Abee Taalib and Muʿaawiyah bin Abee Sufyaan were both noble Companions of the Prophet and fourth and fifth holders of the office of rulership respectively.
 Refer to Al-Maʿloom min Waajibil-’Ilaaqah baynal-Haakim wal-Mahkoom, pp. 22-33.