Is the Prophet Muhammad (peace and blessings be upon him) a martyr, and does he hear those who call upon him in the life of the Barzakh?

The Prophet (peace be upon him) is alive in his grave with a barzakh (interstitial) life, in which he enjoys the blessings Allah has prepared for him. This life is not like his worldly life or his life in the Hereafter. He died just like other prophets, as indicated by the verses (of the Qur’an). The Companions washed him, prayed over him, and buried him. Fatimah (may Allah be pleased with her) requested her inheritance, the Companions gathered to choose a successor, and they did not go to his grave to consult him regarding tribulations.

His barzakh life is specific to prophets and martyrs. It is not like the life of this world, in which the soul separates from the body. The general rule is that the dead do not hear the words of the living, except for what has been exempted. It has not been proven that the Prophet hears every supplication or call, except for the conveyance of prayers and salutations from those who send them upon him. However, supplicating to the Prophet and asking him directly is shirk (polytheism).