Know that thinking is needed to remember what was forgotten, and to think about future benefits. However if thinking is about that which is not fruitful it will be harmful, and if it is excessive it will exhaust the body.
The hypocrites say, "Scholars should leave thinking for some time, lest they exhaust their bodies." I said, a wise person should not stop thinking about what he can attain. However when a layman thinks of becoming the Caliph, that he is as knowledgeable as Abu Hanifah or Al-Shafii, that he is an ascetic exactly like Bishr al-Hafi and Maruf al-Karkhi, to have the wealth of Abdul Rahman ibn Awf, these thoughts exhaust the body, especially if he is only thinking and is idle (instead of working hard to achieve what he wants). A person should rather think about that which is possible for him to achieve, and what he can attain from good deeds. He should also think about his struggle against evil. For many sinners reflected on their consequences and repented, many kings reflected on the vanity of this life, to became ascetic.
Ibn Abbas (ra) said, "Praying two rakat with contemplation is better than praying all night while the heart is heedless." [Ibn al-Mubarak]
Umm al-Darda (ra) was asked, "What was the best deed of Abul-Darda?" She said, "Contemplation and thoughtfulness." [Ibn al-Mubarak]
Malik ibn Dinar stood on his feet praying until dawn and said, "The people of the hellfire, in their chains and iron collars, kept presenting to me until dawn."
Some wise men used to say, "Warding off thinking brings blindness."
The Virtue of the Mind
Dispraise of Hawa (desires)
The Difference Between the Perspective of Mind and the Perspective of Hawa
Averting Passionate Love (Ishq)
Averting Gluttony (Sharah)
Refusing to take a Position of Authority in this world
Prohibition on Squandering
Elucidation on the Amount of Earnings and Expenditure
Dispraise of Lying
Averting Riya (Insincerity and Pretentiousness)
Averting Excessive Thinking
Averting Excessive Sadness
Averting Ghamm (Grief) and Hamm (Worry)
Averting Excessive Fear and Cautiousness of Death
Averting Excessive Happiness
Identifying One's Flaws
Motivating a Low Endeavor
Disciplining and Handling Family and Slaves
Consorting with People
Flawlessness of Character