Is it the case that supplicating for the sick person seven times with "I ask Almighty Allah, Lord of the Magnificent Throne, to cure you" will not heal him if his time of death has come?

The believer must supplicate to Allah with certainty in His ability to answer, and he must have a good opinion of Allah, be resolute in his request, magnify his desire, and repel the whispers of despair and despondency. Supplication for the sick is legislated as long as signs of death have not appeared, for it may be a cause for healing.