Musannaf Ibn Abi Shayba 36:224

'Isa ibn Yunus narrated to us, from Muhammad ibn Ishaq, who said: My father informed me, from men of Banu Salimah, who said: When Mu'awiyah diverted his spring which passes over the graves of the martyrs, it flowed over them, so their graves became exposed. He called out for help regarding them, so we brought them out, and they were bending as if they had died only yesterday. Upon them were two garments, and they had covered their faces and their feet with the plant of Adhkhir.