Does the petitioner's coveting of Paradise and fear of Hell contradict the sincerity of his repentance to Allah Almighty, or is insincerity only present in the case of a worldly motive?

"Seeking mercy and entry into Paradise, and fearing punishment, does not contradict the sincerity of repentance and the worship of Allah; rather, it is the very purpose of repentance. The Quran and Sunnah are replete with encouragement and deterrence, such as His (Allah's) saying: 'And invoke Him with fear and hope,' and His saying about His prophets: 'Indeed, they used to hasten to good deeds and supplicate Us with hope and fear, and they were to Us humbly submissive.' Repentance is remorse for what has passed, abstaining from sin, and the intention not to return to it. It is valid even if it is motivated by the fear of Hellfire or the desire for Paradise."