Answer
(Fatwa: 693/693=M/1429
The Prophet (صلى الله عليه وسلم) is in his grave in Madinah. The companions (Sahaba, may Allah be pleased with them) buried the Prophet (صلى الله عليه وسلم) because he had passed away, as the Holy Quran said: إنك ميت وإنهم ميتون (الأيه)
And occurring death is not against Prophet-hood. There were many prophets before the Prophet (صلى الله عليه وسلم) who tasted death. The life of the Prophet (صلى الله عليه وسلم) in grave is Barzakhi (transitional).
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband