Musannaf Ibn Abi Shayba 13:1112

Abu Bakr narrated to us, he said: Hafs narrated to us, from Hajjaj, from Abd al-Malik ibn al-Mughira, he said: Najdah wrote to Ibn Abbas asking him about the elderly man whose intellect has departed or who has become senile. He wrote back to him: "If his intellect has departed or he has become senile, place him under interdiction (hajr)."