This excerpt is taken from Sheikh Abu Hamza Abdul Khaliq Siddiqi's book Sahih Fazail-e-Amaal.
Allah Almighty says:
﴿وَسَارِعُوا إِلَىٰ مَغْفِرَةٍ مِّن رَّبِّكُمْ وَجَنَّةٍ عَرْضُهَا السَّمَاوَاتُ وَالْأَرْضُ أُعِدَّتْ لِلْمُتَّقِينَ. الَّذِينَ يُنفِقُونَ فِي السَّرَّاءِ وَالضَّرَّاءِ وَالْكَاظِمِينَ الْغَيْظَ وَالْعَافِينَ عَنِ النَّاسِ ۗ وَاللَّهُ يُحِبُّ الْمُحْسِنِينَ.﴾
And hasten to forgiveness from your Lord and a garden as wide as the heavens and earth, prepared for the righteous. Those who spend [in the cause of Allah] during ease and hardship and who restrain anger and who pardon the people - and Allah loves the doers of good.
Reference: (3-Al Imran:133,134)
﴿يَا أَيُّهَا الَّذِينَ آمَنُوا إِنَّ مِنْ أَزْوَاجِكُمْ وَأَوْلَادِكُمْ عَدُوًّا لَّكُمْ فَاحْذَرُوهُمْ ۚ وَإِن تَعْفُوا وَتَصْفَحُوا وَتَغْفِرُوا فَإِنَّ اللَّهَ غَفُورٌ رَّحِيمٌ﴾
"O you who have believed, indeed among your wives and your children are enemies to you, so beware of them. But if you pardon and overlook and forgive - then indeed, Allah is Forgiving and Merciful."
Reference: (64-At-Taghabun:14)
Sheikh Abdul Rahman Nasir As-Sa'di (may Allah have mercy on him) states:
Because the reward of an action is of the same kind, whoever pardons, Allah pardons him; whoever overlooks, Allah overlooks him. Whoever deals with Allah in a matter that He likes and deals with His servants in a way they like and that benefits them, then he succeeds in gaining the love of Allah and the love of His servants, and his affairs are protected.
Reference: (Tafseer As-Sa'di translated: 3/2785)
عن حذيفة رضى الله عنه قال: أتي الله تعالى بعبد من عباده آتاه الله مالا ، فقال له: ماذا عملت فى الدنيا؟ قال: ولا يكتمون الله حديثا قال: يا رب! آتيتني مالك ، فكنت أبايع الناس ، وكان من خلقي الجواز، فكنت أتيسر على الموسر ، وأنظر المعسر فقال الله تعالى: أنا أحق بذا منك تجاوزوا عن عبدي
It is narrated from Sayyiduna Hudhaifah (may Allah be pleased with him): "A servant of Allah, who was blessed with wealth, was presented before Allah. Allah asked him: What did you do in the world? Sayyiduna Hudhaifah (may Allah be pleased with him) recited this verse of the Quran: 'And they will not be able to hide anything from Allah.' He replied: O Lord! You gave me wealth, I used to trade with people and my habit was to pardon. So I was easy on the prosperous and gave respite to the needy. Then Allah said: I am more deserving of that pardon than you. Pardon My servant."
Reference: Sahih Muslim, Book of Sales, Chapter: The Virtue of Giving Respite to the Debtor, No: 1560/29
عن أبى هريرة رضى الله عنه أن رسول الله صلى الله عليه وسلم قال: كان رجل يداين الناس ، وكان يقول لفتاه: إذا أتيت معسرا فتجاوز عنه ، لعل الله أن يتجاوز عنا ، فلقي الله تعالى فتجاوز عنه
It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "A man used to lend people money and used to tell his servant: When you go to someone who is in difficulty (to collect the debt), be gentle and pardon him, perhaps Allah will pardon us as well. So when he met Allah, Allah forgave him."
Reference: Sahih Bukhari, Book of Sales, Chapter: Who Gives Respite to the Debtor, No: 2078 - Sahih Muslim, Book of Sales, Chapter: The Virtue of Giving Respite to the Debtor, No: 1562.
عن أبى قتادة رضى الله عنه قال: سمعت رسول الله صلى الله عليه وسلم يقول:من سره أن ينجيه الله من كرب يوم القيامة، فلينفس عن معسر أو يضع عنه
It is narrated from Sayyiduna Abu Qatadah (may Allah be pleased with him) that I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever likes that Allah saves him from the anxieties of the Day of Resurrection, let him give respite to the debtor or forgive his debt."
Reference: Sahih Muslim, Book of Sales, Chapter: The Virtue of Giving Respite to the Debtor, No: 1563.