Hadhrat Ali (peace be upon him) passed away in Kufa albeit there are different opinions regarding his burial place. Some say that since the rioters were very mischievous, therefore his burial was made in secrecy. According to Hafiz ibn Kasir, the acceptable and reliable sources indicate that he was buried secretly inside the capital Kufa while some Shiah say that the grave of Hadthrat Ali (peace be upon him) is in Najaf. Besides this, there are several opinions concerning the burial of Hadhtrat Ali (peace be upon him) (Al-Bidaya w Al- Nihaya, 329/33).
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband