What is the ruling on repeatedly repenting sincerely from fornication for someone who has relapsed into it after a previous repentance, and could persistent thoughts about it be due to demonic possession, by analogy with what is mentioned concerning those who consume usury?

Adultery is one of the gravest sins, but Allah's mercy is vast, and He accepts sincere repentance that erases the sin. Its conditions are: desisting from the sin, regretting it, and resolving not to return to it, while also concealing one's sin. Allah loves those who repent and rejoices in their repentance. Sincere repentance is accepted even if the sin is repeated. The repentant person should avoid the causes of sin, hasten to marry, occupy their time with what is beneficial, keep company with the righteous, and frequently seek forgiveness and make supplications. Indeed, Satan has no authority over those who put their trust in Allah.