Abdullah bin Ma’qil says: I went with my father to Sayyiduna Abdullah bin Mas’ud (may Allah be pleased with him). He asked: Have you heard the Messenger of Allah (peace and blessings be upon him) say: Remorse is repentance? He said: Yes.
Hadith Referenceالفتح الربانی / كتاب التوبة / 10175
Hadith Gradingمحدثین:صحیح
Hadith Takhrij«صحيح، أخرجه ابن ماجه: 4252، (انظر مسند أحمد ترقيم الرسالة: 3568 ترقیم بيت الأفكار الدولية: 3568»
Brief Explanation
Benefits: … If the sin pertains to the rights of Allah Ta'ala, then for the acceptance of repentance from such a sin there are three conditions: (1) to abandon that sin, (2) to express remorse over it, and (3) to firmly resolve not to commit it again in the future. And if the sin pertains to the rights of the servants (i.e., other people), then there are four conditions: the aforementioned three, and the fourth is that the right of the rightful person be fulfilled and some form of settlement be made with him.
The central condition is remorse; when a Muslim feels remorse before Allah Ta'ala over his mistake, then there is hope that Allah Ta'ala will accept his repentance and he himself will remain protected from committing such a sin in the future.