Remind those who are on their death bed of (There is no true god except Allah)
Abu Hurairah ( may Allah be pleased with him ) narrated that the messenger of Allah ( may the peace and blessings of Allah be upon him ) said:
“Remind those who are on their death bed of the Shahadah “La'Ilaha illall-ah (There is no true god except Allah).” (for them to say it, hoping it will be their last words)”
[Muslim]
It is a part of the Prophetic Sunnah to remind the Muslim when dying with the word of Tawheed ( la ilaha illa Allah ), those who are present with him or one of them shall utter it; perhaps he says it, then it will be the last of his words in this world. His heart will be steadfast with this word until his soul ascends to its Creator. Then it will continue to be a light in his grave until the resurrection when he meets his Lord.
It is desirable for those next to him to utter the two testimonies of faith: I bear witness that there is no god worthy of worship but Allah, I bear witness that Muhammad is the Messenger of Allah.
But we shall not order the dying person to say it; for he may be in distress and then refuses to say it.
He should be reminded by a good man, a loving friend or a merciful father, not to be reminded by an enemy or by the one who envies him because one normally responds to those whom he loves.
Please note that the supplication at this time is an intercession for the dying person, because the angels say Ameen after his supplication, so that his supplication most likely will be answered.
Umm Salamah (May Allah be pleased with her):
The Messenger of Allah ( may the peace and blessings of Allah be upon him ) said, "When you visit a sick or a dying person, you should utter good words because the angels say `Amin' at what you say