abd-quote

To be content with a thing doesn’t mean that you are personally happy with it. It means that: I am content with God, my Lord, who has ordained this for me. We can be content in happiness, and content in sadness. All the things that transpire in our lives are from God. He willed for it to be. Contentment is a type of submission: I have no complaints against Him, and I can do the best in the situation that I am in, and I will seek to find the wisdom that God has in this.
—  Shaykh Dr. Umar Faruq Abd-Allah
Whenever someone puts his knowledge into practice, it becomes a doorway between him and Allah (Almighty and Glorious is He), through which his heart enters into His presence. As for you, O learned one, you are preoccupied with idle gossip and accumulating wealth, instead of putting your knowledge into practice, so you will surely possess only the outer form of it, without the inner content.
— 

Shaykh Abd Al Qadir Al Jilani (may God be pleased with him)

[The Sublime Revelation, Thirteenth Discourse]

O young man! Do all that you can to obey Allah, your Lord. Make strenuous efforts to give to the person who deprives you, maintain a connection with the person who cuts you off, and pardon the person who wrongs you. Make every effort to ensure that your body is with the servants but your heart is with the Lord of the servants. Do all that you can to speak the truth and never tell lies. Make strenuous efforts to work with sincerity and avoid hypocrisy. Luqmān the Wise used to say: “O my son, do not put on a show to impress people for you will not meet Allah (mighty and glorified is He) as long as your heart is infidel!”
—  Shaykh Abd Al Qadir Al Jilani