What is the ruling on saying "My Lord, forgive me and my parents" while sitting between the two prostrations in prayer if the parents do not pray?

Supplicating for one's parents and seeking forgiveness for them is prescribed and beneficial, both during their lifetime and after their death, based on Allah's saying: "And say, 'My Lord, have mercy upon them as they nurtured me when I was small.'" If the parents do not deny the obligation of prayer, then they are not disbelievers, and it is permissible to seek forgiveness for them. However, if they deny the obligation of prayer, they are disbelievers. Nevertheless, many scholars permit supplicating for their forgiveness while they are alive, as Al-Qurtubi said: "There is no harm in a man supplicating for his disbelieving parents and seeking forgiveness for them as long as they are alive." Seeking forgiveness between the two prostrations is a Sunnah according to the majority of scholars, and its wording is "Rabbi ighfir li (My Lord, forgive me)."