If a person repents from sins and then returns to them, what should he do and how can he hold on to his repentance?

Question:
If a person repents from sins, and then returns to them after his repentance has lasted for a short time, what is the course of action? And how can he hold on to his repentance? May Allah reward you with good.

Answer:
First, if a Muslim commits a sin, he must repent to Allah (Mighty and Majestic) with sincere repentance. Allah the Exalted said: with sincere companions, with the pure and correct one. It is that which includes three conditions: first, abandoning the sin, meaning leaving the sin permanently; second, resolving not to return to it; and third, feeling regret for the sin that occurred. These conditions are necessary, and repentance is not valid unless these conditions are present. If one of these conditions is missing, the repentance is not valid. If a person repents only with his tongue without leaving the sins, this is not repentance to Allah (Mighty and Majestic). Likewise, if a person repents and leaves the sins temporarily while intending to return to them, this is also not repentance, but merely a temporary abandonment of the sins, which does not benefit its owner in any way. Similarly, if a person does not feel regret for previous sins, but rather takes pride in them or does not regret them, this is evidence of the insincerity of his repentance, because one who repents from sins means that he hates them and detests them. If he does not regret them, he does not hate them, and consequently, his repentance is not valid.
Added to this is a fourth condition, which is if the sin is an injustice between him and people, and he has transgressed against someone in their honor, wealth, or body, it is required that he return the injustices to their owners and seek their forgiveness, because this is the right of a creation, and it is not dropped from him except by returning it to its owner or the owner forgiving him. These are the conditions that are necessary in repentance. If a person repents with a valid repentance meeting its conditions, and it happens that he falls into the sin again, he must repeat the repentance with its sincere conditions, and he must not despair of the mercy of Allah (Mighty and Majestic) or say, "I repented and then returned," and then despair of Allah's mercy and abandon repentance. No, he must repent, even if his sins and disobedience are repeated, because whenever he disobeys Allah, he repents to Allah (Mighty and Majestic) with a valid repentance, and Allah accepts the repentance of whoever repents, even if the sins and disobedience are many. The saying of Allah, Glorified and Exalted: So the result is that he renews his repentance for every sin and repents to Allah, Glorified and Exalted, and he must abstain from sins and disobedience. But if it happens that his soul, which commands evil, and his Shaytan overcome him and he falls into sin again, he must repeat the repentance and repeat the treatment, and Allah accepts the repentance of whoever repents. Yes. May Allah reward you with good, and may He do you good.