Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) said:
"The expiation for sin is remorse."
The Prophet (peace and blessings be upon him) also said:
"If you people did not sin, Allah Almighty would bring a people who would sin, and Allah Almighty would forgive them."
Ahmad recorded it, and at-Tabarani recorded it in abridged form with only these words:
"The expiation for sin is remorse."
At-Tabarani recorded this in al-Mu'jam al-Kabir and al-Mu'jam al-Awsat, and al-Bazzar also recorded it. Its chain contains a narrator, Yahya bin Amr bin Malik al-Nukri, who is da'if (weak), though he has been declared trustworthy; the rest of its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب التوبة / 17625
Hadith Gradingمحدثین:إسنادہ ضعیف
Hadith Takhrij«اخرجه البزار فى المسند (3250) اخرجه الطبراني فى المعجم الكبير (12794) اخرجه احمد فى المسند (2623) ، أخرجه مسند أحمد برقم: 2618، وأخرجه المعجم الكبير للطبراني برقم: 12795، وأخرجه المعجم الأوسط للطبراني برقم: 2397»