Musnad Ahmad 27:1452

Mu'ammal narrated to us, Sufyan narrated to us, from Abdullah ibn Dinar, who said: I heard Ibn Umar say: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Your lifespan in relation to the lifespan of those who were before you is like what is between the Asr prayer and the setting of the sun."