The Salaf and the Way They Valued TimeSource: 'Wisdom of the Wise' by 'Abdul-'Aziz ibn Nasir al-Jalil & Baha Addin ibn Fatah Aqeel
Al-Hasan al-Basri said: "Oh son of Adam, you are but few days, whenever a day is gone, part of you is gone too." 
Al-Hasan al-Basri said: "I met some people who were more stingy with their time than their money." 
Al-Hasan al-Basri advised his companions saying: 'Do not be occupied with ephemeral worldly pleasure and forget the Hereafter, your life is short, so hurry up and do not postpone today's work till tomorrow, because you do not know when you will die and meet Allah." 
Al-Qasim ibn Asa'kir was informed that Sulaim ibn Ayyub used to give much importance to his time. He never wasted any time without some useful acts. He either wrote books, gave lectures, or read." 
Abu al-Wafa' Ali ibn Aqeel said: 'I am not allowed to waste an hour of my life. Even when I am not giving lectures or reading, my mind will still be occupied with some issues while I am lying down; and I will not get up until I find something useful to write. And I still find myself striving for knowledge in my eighties more than when I was in my twenties.' 
 Adh-Dhahabi, "Siyar A'laam an-Nubalaa" (4/585).
 Al-Baghawi, "Sharh as-Sunnah" (14/225).
 Hilyat al-Awliya' (2/140).
 Adh-Dhahabi, "Siyar A'laam an-Nubalaa" (17/646).
 Ibn al-Jawzi, "Al-Muntadham" (9/214).
To read this article in spanish click here