Ibn al-Jawzi's advice to his son

"Know, dear son, that days are but hours, and hours are but breaths, and every soul is a container, hence let not any breath pass without any benefit, such as on the Day of Judgement you find an empty container and feel regret!
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Be aware of every hour and how it passes, and only spend it in the best possible way; do not neglect yourself, but render it accustomed to the noblest and best of actions, and send to your grave that which will please you when you arrive to it."
- Imam Ibn al-Jawzi rahimahullah in his letter of advice to his son, "Laftat al-Kabid fee Naseehat al-Walad.

لفتة الكبد في نصيحة الولد
للإمام ابن الجوزي يوصي فيها ولده
واعلم يا بني أن الأيام تبسُطُ ساعاتٍ، والساعاتُ تبسُط أنفاسًا، وكلُ نفَسٍ خزانة، فاحذر أن تُذهِبَ نفسًا في غير شيء، فترى يوم القيامة خزانةً فارغة فتندم

If I find the second paragraph in its original, I'll post it here too, inshaa Allah. The letter in its entirety can be found here (the original Arabic text). It is several pages long, mashaa Allah.