The words 'isolation' and 'seclusion' have a special meaning in our religion: to stay away from evil and its perpetrators, and to keep those who are foolish at a distance. When you seclude yourself from evil in this manner, you will have an opportunity to reflect, to think, to graze in the meadows of enlightenment.
When you isolate yourself from things that divert you from Allah's obedience, you are giving youself a dose of medicine, one that doctors of the heart have found to be a most potent cure. When you seclude yourself from evil and idleness, your brain is stimulated into action. The results are increases in faith, repentance, and remembrance of Allah, the Most Merciful.
However, some gatherings are not only recommended, but necessary: the congregational prayer, circles of learning, and all gatherings of righteousness. As for gatherings wherein frivolity and shallowness prevail, be wary of them. Take flight from such gatherings, weep over your wrongdoing, hold your tongue, and be content within the boundaries of your home. By mixing with others based on foolish motives, you endanger the stability and soundness of your mind, for the people you indiscriminately mix with are likely to be experts at wasting time, masters at spreading lies, and skilled in spreading both trouble and mischief. "Had they marched out with you, they would have added to you nothing except disorder; and they and they would have hurried about in your midst [spreading corruption] and sowing sedition among you..." (Qur'an 9:47)
I advise you to fortify yourself to your purpose and isolate yourself in your room, except when you leave it to speak well or to do well. When you apply this advice, you will find that your heart has returned to you. So use your time well and save your life from being wasted. Hold your tongue from backbiting, free your heart from anxiety, and preserve your ears from profanity.
Those who have nothing to do with their lives are the same people who spend most of their time spreading rumors and falsehood, mainly because their minds are devoid of beneficial thoughts: “They are content to be with those [the women] who sit behind [at home]. Their hearts are sealed up [from right guidance] so they understand not.” (Qur'an 9:87)
When you find yourself to be idle, prepare for depression and despair, because idleness allows your mind to wander in the past, the present, and the future, with all of their difficulties. Therefore, my sincere advice to you is to perform fruitful acts instead of being idle, for idleness is a slow and veiled form of suicide.
Idleness is like the slow torture that is inflicted upon prisoners in China: they are placed under a tap, from which a drop of water falls only after every hour. During the period of waiting between drops, many of them lose their minds are driven to insanity.
Being inactive means being negligent of one’s duties. Idleness is an expert thief and your mind is its victim.
Therefore get up now and say a prayer or read a book; praise your Lord, study, write, organize your library, fix something in your house, or benefit others so that you can put an end to your inactivity. I say this only because I sincerely wish for you betterment.
Destroy boredom by working. When you apply this simple precept alone, you will have traveled at least fifty percent of the way towards happiness. Look at farmers, carpenters, and the bread-maker, and observe how, when they are working, they recite words as melodious as the singing of birds, because they are content. Afterwards observe yourself and how you toss and turn on your bed wiping away your tears, always miserable, always torturing yourself.