In Bani Israaeel there was a man who had devoted twenty years to Ibaadat and Taa-at (obedience). Then he transgressed for twenty years.
One day when he looked into the mirror he saw some of the hairs in his beard had become grey. Feeling distressed, he supplicated: “O my Allah! If I return to You, will you accept me?”
In response he heard a Voice from a corner of his house saying: “If you come to Us, We come to you. If you abandon Us, We abandon you. If you sin against Us, We grant you respite. If you return to us, We accept you.”
Allah Ta’ala says in the Qur’aan Majeed: “Say (O Muhammad!) to My servants who have committed excesses (sins) on themselves: “Do not despair of the Mercy of Allah, for verily, Allah forgives all sins. Undoubtedly, He is Most Forgiving, Most Merciful.”
(Source: Subulas Salaam, page 44)