Does a deceased person receive prayers for mercy and forgiveness from those other than their children, or is that restricted to righteous offspring? Is it permissible to request prayers for one's mother? And does committing sins negate the quality of righteousness and prevent the reward of prayers from reaching the deceased?

Muslims' supplications for their living and deceased brethren are beneficial and reach them, in emulation of the Prophet's actions (peace be upon him). Therefore, there is no impediment for a Muslim to ask for prayers for himself, his parents, and all Muslims. Committing some sins does not negate the attribute of righteousness from a Muslim if he repents sincerely or if they were minor sins and he did not persist in them, for every son of Adam is a sinner, and the best of sinners are those who repent. Allah transforms the bad deeds of those who repent into good deeds and overlooks minor sins by avoiding major ones.