What benefit does the deceased gain from a large number of people praying over them, and does their intercession include the forgiveness of sins such as abandoning prayer and wronging others?

The large number of people praying for the deceased, supplicating for them, and interceding on their behalf are among the reasons for Allah's forgiveness for them, based on the Prophet's (peace be upon him) hadith: "There is no Muslim who dies and a congregation of Muslims, numbering three rows, prays over him, except that he will be forgiven." And the hadith: "There is no deceased Muslim whom a congregation of one hundred Muslims prays over, all of them interceding for him, except that their intercession for him will be accepted." And the hadith: "There is no Muslim man who dies and forty men who associate nothing with Allah stand over his funeral, except that Allah will accept their intercession for him." Their intercession is their sincere supplication and request for forgiveness for him. As for the rights of people, they must be fulfilled on the Day of Judgment. The fact that martyrdom does not forgive debt indicates that the rights of people are not forgiven except by fulfilling them. These texts are among the texts of promise, through which forgiveness is hoped for those who meet the conditions and for whom there are no impediments, such as dying upon monotheism.