Beware 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.

O you, who spends his lifetime disobeying his Lord, no one amongst your enemies is wicked to you more than you are to yourself

Sins have many side-effects. One of them is that they steal knowledge from you.

Beware 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.

Repel the thought, for if you don't, it becomes an idea. So repel the idea, for if you don't it will become a desire. So fight against that(desire), for if you don't, it will become a determination and a passion. And if you don't repel that, it will become an action. And if you don't replace it with its opposite, it will become a constant habit. So at that point, it will be difficult for you to change it.

Every gulp of air that goes out in a cause other than the cause of Allah will turn to sorrow and regret on the Day of Judgement.

And verily for everything that a slave loses there is a substitute, but the one who loses Allah will never find anything to replace Him.