Musnad Shihab

Explanation - The occurrence of sin and error from a human being is not something astonishing. However, persisting in it and not repenting and seeking forgiveness is certainly a dangerous act. The truly fortunate one is he who repents after committing a sin. The noble scholars (ulama kiram) state that repentance (tawbah) is obligatory (wajib) for every sin. If the sin is related to Allah Ta'ala and does not pertain to the right of any person, then for the acceptance of repentance from such a sin, there are three conditions:
➊ He must abandon the sin from which he is repenting.
➋ He must express regret and shame over it.
➌ He must make a firm resolve never to commit that sin again in the future.
If any one of these three conditions is missing, the repentance will not be valid. And if the sin is related to a human being, then there are four conditions for it: the same three mentioned above, and the fourth is:
➍ He must fulfill the right of the one entitled to it, or the one entitled must forgive him.
In the aforementioned hadith, the importance of the second condition of repentance—regret and shame—has been stated, that expressing regret over a sin is itself a kind of repentance. However, this does not mean that a person should consider only regret to be sufficient and neglect the other matters; this is not so. Rather, for sincere repentance, it is necessary to observe the two conditions mentioned above as well. And Allah knows best.