On the authority of Abdullah ibn Umar (may Allah be pleased with him), who said:
The Messenger of Allah (peace and blessings of Allah be upon him) took me by the shoulder and said, “Be in this world as though you were a stranger or a wayfarer.”
And Ibn Umar (may Allah be pleased with him) used to say, “In the evening do not expect [to live until] the morning, and in the morning do not expect [to live until] the evening. Take [advantage of] your health before times of sickness, and [take advantage of] your life before your death.”
It was related by al-Bukhari.