Qur'an defines a sound heart as turning to and submitting fully to Allah, having fear and love of Allah as much as one can and a sincere faith.
Those who believe and whose hearts find peace in the remembrance of Allah. Only in the remembrance of Allah can the heart find peace. (Surat ar-Ra’d, 28)
A sound heart in the Islamic context means a heart that is purified from all forms of impurity that draw one away from Allah.
Truly Allah has knowledge of the Hour, sends down abundant rain, and knows what is in the womb. And no self knows what it will earn tomorrow, and no self knows in what land it will die. Allah is All-Knowing, All-Aware. (Surah Luqman, 34)
p/s : Allah tahu pe yang kita buat, apa yang kita rasa. Belum terlambat lagi selagi mati. Nasihat untuk yang sedang baca & juga pada diri aku sendiri. Semoga kita sama-sama dapat merasai indah-Nya, manis-Nya iman tuh. :)