63. Sin, which indeed is a poison, is born when a man is wanting in obedience to God and is empty of His love and His affectionate remembrance. The fate of a man whose heart has become cold to the love of God is like that of an uprooted tree, no longer capable of drawing the sap of life from the soil. As such a tree gradually withers and dies out, so, like the dryness of the tree, sin overwhelms the heart. The remedy for this state of dryness, according to the law of nature is of three types:
(1) Love
(2) Istighfar, i.e. seeking forgiveness of Allah. It literally means a desire to bury or to cover, reminding one that as long as the root of the tree is buried in the soil it can hope to bring forth green foliage.
(3) The third remedy is tauba, which means to turn towards God in all humility drawing the sap of life and to bring oneself closer to Him to break loose with the help of righteous deeds from the enveloping cover of sinfulness. Tauba cannot be achieved merely by word of mouth; in fact tauba can be perfected only with the help of righteous deeds. All acts of goodness are aimed at achieving perfection of tauba.
(Sirajuddin Isai ke Char Sawalon ka Jawab: Roohani Khaza'in Vol. 12, p 328-329)