Source:Al-Maqasid
“What we mean by ilm tariq al-akhira (Science of the way to Hereafter) is the knowledge that polishes the mirror (of the heart) from the filth that veils it from Allah the Exalted and from knowing His attributes and actions. It becomes purified and cleansed through refraining from lower desires and by following the Prophets (peace be upon them) in all their states.”
(Imam al Ghazali)