He, may Allah be pleased with him, derived benefit from the Saying of Allāh Most High,

قَدْ أَفْلَحَ مَن زَكَّاهَا (٩) وَقَدْ خَابَ مَن دَسَّاهَا ١٠)
Indeed, the one who purifies it is successful (9)
The one who obscures it is unsuccessful (10)

The nafs of the servant at any instance receives either iślāh (rectification) or ifsād (corruption). The acceptance of either iślāh or ifsād will bring to it’s tazkiyah (purification) or tadsiyah (obscuration) . The acquirement of islāh and taqwīm (rectification) results in it’s purification while acquirement of ifsād results in it’s obscurement.