Musnad Abu Ya'la al-Mawsili 2:57

'Abdullah ibn Muhammad ibn Asma' narrated to us, Mahdi narrated to us, Sa'id al-Jurayri narrated to us, from Abu Nadrah, from Abu Firas, who said: I witnessed 'Umar ibn al-Khattab while he was addressing the people. He said: "O people, a time has come upon me wherein I used to think that whoever recited the Qur'an desired Allah and what is with Him. But now, it is imagined to me that there are people who recite it desiring the people thereby, and desiring the world thereby. Beware, so desire Allah with your deeds. Beware, we used to know you when the revelation was descending, and when the Prophet (may Allah bless him and grant him peace) was among us, and when Allah would inform us of your news. But the revelation has ceased, and the Prophet of Allah has departed. We only know you by what you say to us. Beware, whoever we see good from, we think well of him and love him for it; and whoever we see evil from, we think evil of him and hate him for it. Your inner secrets are between you and your Lord. Beware, I only send my governors to teach you your religion and to teach you your Sunnahs. I do not send them to strike your backs nor to take your wealth. Beware, whoever has any doubt regarding that, let him raise it to me. For by the One in Whose hand is the soul of 'Umar, I will surely exact retribution for you from him." 'Amr ibn al-'As stood up and said: "O Commander of the Faithful, have you considered if you sent one of your governors and he disciplined a man from among his subjects and struck him, would you exact retribution from him?" He said: "Yes, by the One in Whose hand is the soul of 'Umar, I will surely exact retribution from him. Should I not exact retribution when I have seen the Messenger of Allah (may Allah bless him and grant him peace) exact retribution from himself? Beware, do not strike the Muslims, lest you humiliate them. Do not withhold their rights from them, lest you cause them to disbelieve. Do not keep them gathered in military camps, lest you tempt them. And do not settle them in thickets, lest you cause them to be lost."