Musnad Ahmad 32:127

Ibn Abi ‘Adi narrated to us, from Sa‘id, and Ibn Ja‘far, and ‘Abd al-Wahhab al-Khaffaf, from Sa‘id, from Qatadah, from Anas, that the Prophet of Allah, peace and blessings of Allah be upon him, said: "Indeed, I enter into the prayer, and I intend to prolong it, but then I hear the crying of a child, so I shorten my prayer, due to what I know of the intensity of his mother’s distress from his crying."