Muwatta Malik (Yahya)

Imam Malik, may Allah have mercy on him, said: If two or three people are buried in one grave out of necessity, there is no harm in it, but the eldest among them should be placed closest to the Qiblah.

It is narrated from Abdur Rahman bin Abi Sa’sa’ah that the grave of Sayyiduna Amr bin Jamuh (may Allah be pleased with him) and Sayyiduna Abdullah bin Amr Ansari Salmi (may Allah be pleased with him), who were martyred in the Battle of Uhud, was disturbed by the flow of water, and their grave was near the flow. Both were in the same grave, so the grave was dug up in order to remove their bodies and bury them elsewhere. When it was seen, their bodies were as they had been when they were martyred, as if they had died only yesterday. One of them, when he was wounded, had placed his hand on his wound. When they began to bury him, his hand was removed from there, but the hand returned to the same place. When their bodies were exhumed, forty-six years had passed since the Battle of Uhud.