Musnad Abu Ya'la al-Mawsili 152:236

Abu Khaythama narrated to us, Abu ‘Amir al-‘Aqdi narrated to us, Sufyan narrated to us, from Simak ibn Harb, from ‘Abd al-Rahman ibn ‘Abd Allah, from his father, who said: I came to the Messenger of Allah (may Allah bless him and grant him peace) while he was in a tent made of leather, among about forty men. He said: "You will be granted victories, you will be aided, and you will be successful. So whoever among you witnesses that, let him fear Allah, enjoin the good, forbid the evil, and uphold the ties of kinship. Whoever lies about me intentionally, let him take his seat in the Fire. And the likeness of the one who helps his people in something other than the truth is like a camel that has fallen into a well, and he is pulling it out by its tail."