Musnad Ahmad 32:1298

'Abdullah ibn Bakr al-Sahmi narrated to us, Humayd al-Tawil narrated to us, from Anas, who said: The Prophet, peace and blessings of Allah be upon him, was on a road with some of his companions when a woman met him and said: "O Messenger of Allah, I have a need for you." He said: "O mother of so-and-so, sit in whichever side of the paths you wish, and I will sit with you." She did so, and he sat with her until she had fulfilled her need.