Musnad Abu Ya'la al-Mawsili 129:6

Abu Bakr narrated to us, Hushaym narrated to us, Humayd informed us, from Anas, that the Messenger of Allah (may Allah bless him and grant him peace) said: "Verily, I am in the row during prayer, and I hear the sound of a child crying, so I shorten my prayer out of fear that it might be difficult for his mother."