What is Sincere Repentance? How do you know if you are truly repentant?

Allah Most High says, "Turn towards Allah, O believers, every one of you, so that you may be successful."

And He says, "Ask your Lord for forgiveness and then turn in repentance to Him,"

and He says, "O you who believe! Turn in sincere repentance to Allah."

The Prophet (salAllahu alayhi wasalam) said, 'The one who repents from sin is like the one who never sinned.'
[Ibn Maja (3240)]
He also said, 'Remorse is repentance.'
[Ibn Maja (4242) and Ahmad (3387)]

Abu Huraira (radiAllahu anhu) reported that the Messenger of Allah (salAllahu alayhi wasalam) said, "Allah will turn towards anyone who turns in repentance before the sun rises from the place it set."

Imam Barkawi, the great Ottoman Hanafi faqih, grammarian, and sufi, defined repentance (tawba) in his Tariqa al-Muhammadiyya as,

"Going back from desire to sin, with the determination of not returning to it, in exaltation of Allah and out of fear of His punishment." [al-Bariqa fi Sharh al-Tariqa, 3.139]

The Conditions for Repentance

The conditions for repentance are well known:

1. Leaving the sin;
2. Remorse over having committed the sin;
3. Resolve never to return to the sin;
(If it relates to the rights of another person, then to) Return the rights or property one wrongly took. [al-Bariqa fi Sharh al-Tariqa; Riyad al-Salihin]

If these conditions are truly met, then one can expect one's sins to be forgiven. However, one has to be very careful about how sincere one is in fulfilling one's conditions. It is recommended to seek forgiveness a lot, and to repent every time the sin comes to one's mind.

If one keeps repeating the sin, then one should find the root cause(s) of the sin and eliminate them. For example, if one falls into a certain sin because of the company one keeps, then it would be necessary to either stop keeping their company, or to change the nature of one's relationship with them.

So, what is true repentance?

Ibn Hajar mentioned that Qurtubi quoted 23 different definitions of true repentance (al-tawba al-nasuh) in his tafsir. Ibn Hajar mentioned the most important of these:

1. Umar’s words (Allah be pleased with him) that it is, "To sin and then never to return to it."

2. To hate the sin, and the seek forgiveness for it everytime it occurs to one, as Hasan al-Basri (Allah have mercy on him) said.

3. Qatada’s words (Allah have mercy on him), "To be genuine and truthful in one’s repentance," which is what Imam Bukhari chose as the definition of true repentance in his chapter heading.

4. To have sincerity in one’s repentance.

5. To be concerned about one’s repentance not being accepted.

6. To be such that it does not need another repentance after it.

7. To be made out of fear and hope, and be accompanied by consistency in worship.

8. Like the seventh, but with the added condition that one desert those who assisted one in sin.

9. That one’s sin be between one’s eyes. [f: That is, one does not forget it.] [Ibn Hajar, Fath al-Bari]