Shaykh Muhammad bin Saalih al-Uthaymeen rahimahullaah said:
A person should take advantage of his lifetime by [performing] righteous action, because he will regret it – when death comes to him – if a single hour passed him by and he did not draw closer to Allaah the Mighty and Majestic in it.
Every hour that passes you by and you do not draw closer to Allaah by way of it, then it is a waste; because it has gone and you did not benefit from it.
So take advantage of this opportunity by [performing] the prayer, making remembrance of Allaah, reading the Qur·aan, and being attached to Allaah the Mighty and Majestic. Let your heart always be with Allaah the Exalted and Most High.
Your Lord is above the Heavens and you are upon the Earth; so do not be negligent in remembering Allaah upon your tongue, through your actions, or in your heart. For verily this worldly life will pass by, and it will not remain for anyone.
Look at those who preceded you from the previous nations and those who lived aeons ago.
Look at those who preceded you from your own friends – yesterday they were with you; enjoying themselves, eating just like you eat, and drinking just like you drink – and now they are a pledge for their actions, and they are going to be held to account for them.
And exactly the same thing will happen to you; whether your stay in this world is long or short. Allaah the Most High said:
يَآ أَيُّهَا الْإِنْسَانُ إِنَّكَ كَادِحٌ إِلَىٰ رَبِّكَ كَدْحاً فَمُلاَقِيهِ
[[Meaning: O man! You are laboring towards your Lord with your deeds, and you will meet Him with them.]]
So take advantage of this opportunity my brother – take advantage of the opportunity of your lifespan. Nothing will help you on the day of on the Day of Resurrection; not wealth, nor children, nor family. Nothing will help you except if you come to Allaah with a sound heart.
I ask Allaah the Most High to make yourselves and myself from those who come to their Lord with a sound heart; and that He causes us to die upon the correct belief and upon tawheed (monotheism) – verily He is all-Capable over everything.
See: ‘Sharh Riyaadus-Saaliheen’ vol. 5 pp. 153-154