1. Ubaydullaah ibn Adiyy ibn Khiyaar reports: I went to Uthmaan (radiallaahu anhu), whilst he was being besieged and I said to him: You are the ruler of the Muslims in general and you see what has befallen you. We are being led in prayer by a leader of insurrection and we are afraid of being sinful. So Uthmaan said, The prayer is the best of actions which people do so, when the people do good deeds, do good along with them. When they do evil, avoid their evil. Reported by al-Bukhaaree (Eng. trans. 1/376/ch.56).
2. Abdullaah ibn Ahmad ibn Hanbal reports in his Masaail (no.446): I asked my father how many (rakahs) should I pray after Jumuah. He said, If you wish, pray four (rakahs) or, if you wish, pray six rakahs, in twos; that is what I prefer, but, if you pray four, there is no harm. Abu Dawood reports in his Masaail (p.59): I heard Ahmad say, (Regarding) prayer after Jumuah, if one prays four, good. If one prays two, good, and if one prays six, good.