Is there an authentic Hadith stating that whoever says "Ya Hayyu Ya Qayyum, la ilaha illa Anta" (O Ever-Living, O Self-Sustaining, there is no god but You) forty times, his heart will not die on the Day hearts die, as was transmitted from Imam Al-Shatibi about a vision of one of the imams in his dream of the Prophet, may Allah bless him and grant him peace?

Al-Shatibi mentioned that dreams are not given legal rulings unless they are presented to existing Sharia (definition) rulings. If they are consistent with these rulings, then their implications are acted upon; otherwise, they must be abandoned. Their general benefit is to alert one to good or to give glad tidings, not to derive legal rulings. As an example, what was narrated about Al-Kattani (may Allah have mercy on him), who saw the Prophet (peace be upon him) in a dream, advising him to say "O Living, O Sustainer, there is no god but You" forty times daily to revive his heart. This statement is good because dhikr (remembrance of Allah) revives the heart, which is a known matter in Sharia. However, the specification of forty times is not supported by a text, so it is not obligatory, but if it happens to occur, there is no harm.

Seeing the Prophet (peace be upon him) in a dream does not establish Sharia rulings because the religion has been perfected. If the vision is consistent with Sharia, it is a confirmation of a legal matter and a glad tiding, but no new ruling is built upon it. If a person sees the Prophet (peace be upon him) in a dream and he orders him to do something or teaches him a supplication, this is not acted upon unless what came in the dream is consistent with Sharia and known from it beforehand, and no new matter is legislated that was not brought by the Sharia.