Musannaf Ibn Abi Shayba 27:542

Affan narrated to us, he said: Wuhayb narrated to us, he said: Abdullah bin Uthman bin Khuthaym narrated to us, from Sa’id bin Abi Rashid, from Ya’la al-Amiri, that al-Hasan and al-Husayn came running to the Messenger of Allah, may Allah bless him and grant him peace. He embraced them both to himself and said: "Indeed, children are a cause of miserliness and a cause of cowardice."