A mistake is one that is made by mistake (sic) and a crime is one that is done deliberately.
A mistake must obviously be forgiven. A crime is culpable but can also be forgiven. This is the peculiarity of Islamic Law that even a crime as serious as murder can simply be forgiven by the family of the deceased. Mercy is the driving force behind all forgiveness and that is because we all need it. We all need mercy of our fellow humans and we all need the mercy of Allahﷻ because we all make mistakes. The best of us makes mistakes and the best of us are those who make mistakes and seek forgiveness.
Anas ibn Malik (R) reported: Rasoolullahﷺ said, “All of the children of Adam are sinners, and the best of sinners are those who repent.” [Sunan Ibn Majah 4251]
Abu Hurairah(R) reported: Rasoolullahﷺ said, “By the One in Whose Hand my soul is! If you do not commit sins, Allahﷻ would replace you with a people who would commit sins and seek forgiveness from Allahﷻ; and Allahﷻ will certainly forgive them.” [Muslim].
Allahﷻ applauded those who forgive and advised forgiveness and said:
الَّذِينَ يُنفِقُونَ فِي السَّرَّاء وَالضَّرَّاء وَالْكَاظِمِينَ الْغَيْظَ وَالْعَافِينَ عَنِ النَّاسِ وَاللّهُ يُحِبُّ الْمُحْسِنِينَ
A’al Imraan 3: 134. Those who spend [chairty] in prosperity and in adversity, who suppress anger, and who pardon people; verily, Allah loves Al-Muhsinun (people who seek to please Allahﷻ by acting with excellence)
Allahﷻ mentioned the Bani Israeel and that they had reneged on the covenant with Him and disobeyed Him, yet He advised Rasoolullahﷺ to forgive them and overlook their faults. He said:
فَاعْفُ عَنْهُمْ وَاصْفَحْ إِنَّ اللّهَ يُحِبُّ الْمُحْسِنِينَ
Ma’aida 5: 13. ….. But forgive them, and overlook (their misdeeds). Verily, Allah loves Al-Muhsinun.
Rasoolullahﷺ told us: “Whoever conceals [the faults of] a Muslim, Allahﷻ will conceal [his faults] in this life and the Hereafter.”
The matter of concealing the faults of others is mentioned in numerous Ahadith of Rasoolullahﷺ, like this one: “O gathering who believe with their tongues but faith has yet to enter into their hearts, do not backbite the Muslims. And do not search into their private matters. Whoever searches for their private matters will have Allahﷻ follow up his private matters. And whose private matters Allahﷻ follows, He will expose him even [if his act were done] in his house.” [Musnad Ahmad and Abu Dawood]
On the authority of Abu Huraira (R) who reported that Rasoolullahﷺ said, “Whoever relieves a believer’s distress of the distressful aspects of this world, Allahﷻ will rescue him from a difficulty of the difficulties of the Hereafter.
Whoever alleviates [the situation of] one in dire straits who cannot repay his debt, Allahﷻ will alleviate his lot in both this world and in the Hereafter.
Whoever conceals [the faults of] a Muslim, Allahﷻ will conceal [his faults] in this life and the Hereafter. Allahﷻ helps a slave as long as the slave helps his brother.
Whoever follows a path in order to seek knowledge thereby, Allahﷻ will make easy for him, due to that, a path to Jannah.
No people gather together in a house of the houses of Allahﷻ, reciting the Book of Allahﷻ and studying it among themselves, except that tranquility descends upon them, mercy covers them, the angels surround them and Allahﷻ mentions them to those in His presence. Whoever is slowed by his deeds will not be hastened forward by his lineage.” [Muslim]