How can a person become strong in Eemaan–fulfilling the commandments of Allaah and fearful of His Punishment?
This can be (attained) by way of recitation of Allaah’s Book–studying it, pondering upon its meanings and rulings. And by studying the Sunnah of the Prophet (sallal-laahu-alayhi-wasallam) — having knowledge and awareness of the affairs of the Islamic legislation by way of it, acting upon what that necessitates and adhering to it in creed, actions and speech. And to be extremely mindful of (Allaah’s absolute knowledge of whatever you do and wherever you may be), to (nurture) the heart upon awareness of His Greatness, remembrance of the hereafter and what is found in it of recompense, reward, punishment and the severity of its affairs. And to keep the company of those whom (you) know amongst the righteous people and keep away from the people of evil and corruption.
[Fataawaa Lajnah Ad-Daa-imah 1/360: Quoted in Fataawaa Al-Mar’atul Muslimah page27: publishers Daar as-Sahaabah]