ٱلَّذِينَ ءَامَنُوا۟ وَتَطْمَئِنُّ قُلُوبُهُم بِذِكْرِ ٱللَّهِ ۗ أَلَا بِذِكْرِ ٱللَّهِ تَطْمَئِنُّ ٱلْقُلُوبُ
Those who have believed and whose hearts are assured by the remembrance of Allah. Unquestionably, by the remembrance of Allah, hearts are assured (Surat Ar-Raad, v28)
The 2 qualities mentioned in this ayat are belief in Allah and His remembrance. These are actually the qualities of people who repent - turn to Him for forgiveness; come (back) to the straight path. We know this from the previous verse. Allah ends the ayat with a very strong statement. In a very affirmative tone, Allah tells us that only the remembrance of Allah will bring you true peace. Thats the beauty of the quran - the words define the tone. SubhanAllah!
Many a times people have told me how they were not at peace. They didnt use those exact words, but they would say "i'm depressed" or "i feel weird/restless" or similar phrases showing the unrest within themselves. Some even say, everything's fine but im still depressed. I, myself have felt that way at certain times. The problem is we dont know what we are lacking is... peace. Most of us have some or the other difficult circumstance. For some, the challenges are more trying. Some seem to be stuck in a rut of challenges and arent able to get themselves out of one, when they are faced with yet another. SubhanAllah.
Recently this ayat came in front of me. Allahu Akbar I knew what was lacking from people's lives was the remembrance of Allah. When a person is somewhat attached to Allah, through salah or through good deeds - Allah wants that slave of His to completely enter subservience, to draw him nearer. This need to be nearer to Allah, causes unrest within a person. This is from the mercy of Allah. It is upto us however, to recognize this unrest and then channel it correctly. That slight attachment to Allah, is what causes us to seek for a way. The key is to know "what" you are seeking.
We all feel this unrest sometime, and that should be our clue that we are missing something in our daily routine.
How do we remember Allah? Make istighfar, do tasbeeh, read your duas for entering/leaving the home, etc. This is one kind of remembrance. Another is to realise the wrongs in your life, and make the changes for the pleasure of Allah SWT. Give in charity, get involved in the work of Allah SWT. Make every limb of yours work for Allah SWT. Make dua to Allah, and rely solely upon Him.
Anything and everything you do for the sake of Allah, is His remembrance. Nothing else you do will get you peace - although on the surface you may have the best of everything. Above all know that true peace and happiness will only be attained in jannah. That, in itself, brings peace to a mo'min.