What is the way to expiate sin and breaking the covenant with Allah so that the heart may find peace and salvation through Allah's mercy?

The fear of Allah is a sign of true faith, and a believer must beware of Allah's punishment and avoid what displeases Him. Fear is commendable if it motivates good deeds, and blameworthy if it leads to despair of Allah's mercy. If you fall into a sin, hasten to sincere repentance that fulfills all its conditions, for Allah rejoices at the repentance of His servant. Have a good opinion of Allah that He will accept your repentance, and combine fear with hope. Increasing good deeds after sin is good, for "indeed, good deeds do away with evil deeds." The generosity and forgiveness of Allah are immense, and no sin is too great for Him when its perpetrator repents.