Is it possible for Allah the Almighty not to punish the perpetrator of a great sin and to grant him what he wishes, while punishing another for the same sin and causing him to suffer severe torment and illness?

This world is a place of action, and the Hereafter is a place of recompense. Allah may grant the disobedient worldly provisions as a gradual enticement (istidraj), or He may hasten some punishment for them so that they may return and repent. Fortunate is the one who hastens to repent. No matter how great the sins, Allah accepts the repentance of the sincere penitent. He loves those who repent frequently and transforms their evil deeds into good ones, for "the one who repents from sin is like one who has no sin." Repentance involves abandoning the sin, regretting it, and resolving not to return to it. One must not despair of Allah's mercy, because "none despairs of the relief of Allah except the disbelieving people." One must associate with righteous women and avoid the people of innovation. Salvation is achieved by seeking refuge in Allah alone and adhering to the Sunnah of the Prophet (peace and blessings be upon him) and his companions.