Musnad Ahmad 770:62

Waki' narrated to us, Sufyan narrated to us, from Abu al-Yaqzan 'Uthman ibn 'Umayr al-Bajali, from Zadhan, from Jarir ibn 'Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The *lahd* (niche grave) is for us, and the *shaqq* (trench grave) is for the People of the Book."