If I say to one of them, "May Allah have mercy on him," does that mean the person will die, and is this phrase specific to the deceased?

The questioner : Now, if people invoke mercy for a person, saying "May Allah have mercy on you" or "May Allah have mercy on him," and he is still alive, do they say they have shown him mercy, or that he has died?

The Shaykh : No, you do not say that. This is specific to the Messenger (peace and blessings be upon him).

The questioner : Well, and the negation is that they honor some people with it.

The Shaykh : No, this is just a custom, a habit.