This tomb is located in a city called Kakhak, 24 km. south of Gonabad. This is the tomb of Mohammad Ben Jafar al Sadeq, the uncle of Imam Reza, which was reputedly known as “Mohammad Al Abed”. The structure was erected during the end of the Saljuqi era and was repaired during Teimoorian and Safavid eras.
On northern entance an inscription is observed, on which the date of 980 and name of Shah Esmail Safavid is en-carved. In the year 1968 AD, the structure was damaged during an earthquake but thence was repaired.
The structure of mausoleum consists of a square hall with an entrance in each side, two tetragonal halls in west and east, a portico in the middle of northern section and two small porticoes in either sides and an open area in front of the portico.