Musnad Abu Ya'la al-Mawsili 42:59

Abu Bakr narrated to us, Bakr bin Abd al-Rahman narrated to us, Isa bin al-Mukhtar informed us, from Abu Layla, from al-Awfi, from Abu Sa’id, from the Prophet, peace be upon him, who said: "The child is the fruit of the heart, and indeed he is a cause of cowardice, a cause of stinginess, and a cause of sadness."