What is the legal formula for instructing the dead (talqīn al-mawtā) and is it legitimate or an innovation?

It is recommended to prompt the dying person to say the Shahada (testimony of faith), unlike prompting the deceased after burial, which is not legislated. The hadith reported concerning it is weak. What is legislated is to supplicate for the deceased and seek forgiveness for them after burial, based on the Prophet's (peace and blessings be upon him) saying: "Ask for forgiveness for your brother and supplicate for him to be firm, for indeed he is now being questioned."