I repented from a sin, then I returned to it. Was my repentance not sincere?

Question:
May Allah reward you with good and do you well. You say that I made a mistake once and repented from it, then I returned to the mistake again and repented, but I am still afraid. Despite the fact that I call upon Allah (Glorified and Exalted is He) for my repentance to be a sincere repentance, I am still not at ease, despite the fact that I call upon Him a lot. Please guide us, may Allah reward you with good.

Answer:
It is obligatory for the Muslim, when he repents from a sin, to abandon it, to stay away from its causes and means, and to seek help from Allah to leave it. If it happens that he falls into it a second time, he should not despair of the mercy of Allah. He must repent and repeat the repentance, but he must resolve not to return to it, seek help from Allah, stay away from the causes that lead him to this disobedience, and abandon the means that lead to it. However, if he does this and repents with sincerity, faith, and desire for what is with Allah, and then falls into the disobedience a second time, he should not despair of the mercy of Allah nor abandon repentance; rather, he should repeat the repentance every time the sin is repeated. Allah is Forgiving and Merciful to whoever repents to Him. Yes.