It is reported from ‘Alî b. Abî Tâlib –رضي الله عنه – that he said:
The thing I fear for you most is following desires and having extensive hopes (about this worldly life). Following one’s desires blocks you from the truth, and having extensive hopes makes you forget the hereafter. Verily, this worldly life is departing and the hereafter is approaching and each of them has its children. So be children of the hereafter, not children of this world, for today there are (opportunities to do) deeds and there is no reckoning, but tomorrow there will be reckoning and no deeds.
Quoted by Al-Bukhârî, Al-Sahîh, The Book of Raqâ`iq without the first sentence. Reported in its entirety by Abû Nu’aym, Hilyah Al-Awliyâ` Vol.1 p40, and others