Allah Taãla says in the Noble Qurãn, 'You are the best of nations sent to man. You command good and forbid evil and you believe in Allah'. (Aali Imraan).
Allah Taãla states that one reason for this Ummah being titled as the best of Ummah, is the practice of commanding good and preventing evil'.
The Prophet (sal Allahu alayhi wa sallam) said: “Allah, Blessed and Exalted is He, says, ‘O son of Adam, as long as you call on Me, I shall forgive you of what you have done, and think nothing of it. O son of Adam, even if your sins were to reach up to the clouds in the sky, and then you were to ask for My forgiveness, I would forgive you and think nothing of it. O son of Adam, even if you were to come to Me with sins nearly as great as the earth, and then you were to meet Me after death, not worshiping anything besides Me, I would bring you forgiveness nearly as great as the earth.’” [Tirmidhi]
Commentary: "Allah (subhana wa ta’ala) loves it when people ask Him to forgive their sins. He is overjoyed with their repentance, since He hates to punish anybody. At the slightest excuse He washes people’s sins away. The only condition is that the human being must truly regret in his/her heart that they did what they did. The sinner should be ashamed of their misdeeds, and discontinue committing such sins.
If the resolve to avoid the sin is not there then one has not actually repented.In this hadith, Allah (subhana wa ta’ala) tells us that no matter how many a person’s sins are, should they even reach the sky in heaps, Allah would forgive the sinner if they were to turn to Allah in repentance. In a different hadith, the Prophet (sal Allahu alayhi wa sallam) told us that Allah’s bounty is so vast that He would actually convert all the sins into good deeds, should the person truly repent. We should not postpone repenting of our sins and reforming ourselves to when we become old, since nobody knows when they will die."