Musnad Ahmad 27:1990

Abdullah ibn al-Harith narrated to us, from Ibn Jurayj, who said: Sulayman ibn Musa said to me: Nafi’ narrated to us, that Ibn Umar used to say: The Messenger of Allah, may Allah bless him and grant him peace, said: "Spread the greeting of peace, provide food, and be brothers as Allah, the Almighty and Majestic, has commanded you."