Musnad Abu Ya'la al-Mawsili 115:318

Abu Musa narrated to us, Ibn Abi Adi and Abd al-A’la narrated to us, from Sa’id, from Qatadah, from Anas, that the Prophet (peace and blessings of Allah be upon him) said: "Indeed, I enter into the prayer intending to prolong it, 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 because of his crying."