Sahih al-Bukhari Book 10, Hadith 91
The Prophet (ﷺ) said to Abu-Dhar, "Listen and obey (your chief) even if he is an Ethiopian with a head
like a raisin."
I went to 'Uthman bin Affan while he was besieged, and said to him, "You are the chief of all Muslims in general and you see what has befallen you. We are led in the Salat (prayer) by a leader of Al-Fitan (trials and afflictions etc.) and we are afraid of being sinful in following him." 'Uthman said. "As-Salat (the prayers) is the best of all deeds so when the people do good deeds do the same with them and when they do bad deeds, avoid those bad deeds." Az-Zuhri said, "In our opinion one should not offer Salat behind an effeminate person unless there is no alternative."
Once I passed the night in the house of my aunt Maimuna. Allah's Messenger (ﷺ) offered the `Isha' prayer and then came to the house and offered four rak`at an slept. Later on, he woke up and stood for the prayer and I stood on his left side. He drew me to his right and prayed five rak`at and then two. He then slept till I heard him snoring (or heard his breath sounds). Afterwards he went out for the morning prayer.