Allah is Most Forgiving:

Announce, (O Prophet) to My slaves that verily I am the Forgiving, the Merciful. (Qur’an 15: 49)

“Those who avoid the greater sins and immoralities, only [committing] lesser offences, verily, your Lord is ample in forgiveness. [Quran 53:32]

In one instance, the Quran refers to Allah as being “the best of those who forgive” when relating where Moses offers the following supplication: You are our Protector: so forgive us and give us Your mercy; for you are the best of those who forgive. (Quran 7: 155)

Forgive people to gain Allah’s forgiveness

But if you pardon, overlook, and forgive their faults, then Allah is truly All-Forgiving, Most Merciful. [Quran 64:14]

Messenger of Allah (صلى الله عليه وسلم (said: The gates of Paradise will be opened on Mondays and on Thursdays, and every servant who associates nothing with Allah will be forgiven, except for the man who has a grudge against his brother. it will be said: Delay these two until they are reconciled; delay these two until they are reconciled. [Abu Dawud]

Dua for Forgiveness

Our Lord! Forgive us and our fellow believers who preceded us in faith, and do not allow any resentments into our hearts towards those who believe. Our Lord! Indeed, You are Ever Gracious, Most Merciful. [Quran 59:10]