Musnad Ahmad 30:2648

Waki’ narrated to us, he said: Sufyan narrated to us, from Abdullah ibn Dhakwan, from al-A’raj, from Abu Hurairah, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The heart of the old man remains young regarding the love of two things: the accumulation of wealth, and the length of life."