Musannaf Ibn Abi Shaybah

Hazrat Hisham bin Urwah narrates from the jurists of the people of Madinah that there were two men in Madinah who used to dig graves; one of them would make a grave with a trench (shaqq) and the other would make a niche (lahd). When the Noble Prophet (peace and blessings be upon him) departed from this world, the companions said, "Go and call whichever of them you find, and tell him to come and do his work." Then the man who used to dig the niche (lahd) came, and the companions instructed him to dig a niche for the Noble Prophet (peace and blessings be upon him).