Musnad Ahmad 32:1546

Ya'qub narrated to us, my father narrated to us, from Muhammad ibn Ishaq, who said: Humayd al-Tawil narrated to me, from Anas ibn Malik, who said: "The prayer was called (iqamah) during the time of the Messenger of Allah, may Allah bless him and grant him peace, and there had been something (a dispute) between the wives of the Messenger of Allah, may Allah bless him and grant him peace. He said: So the Messenger of Allah, may Allah bless him and grant him peace, began to turn some of them away from others. He said: Then Abu Bakr came to him and said: 'O Messenger of Allah, throw dust into their mouths, and go out to the prayer.'"