It is narrated from Sayyiduna al-Hakam bin al-Harith al-Sulami (may Allah be pleased with him) that he took part in three military expeditions with the Messenger of Allah (peace and blessings be upon him). (The narrator Atiyyah) said: He said to us: "When you have buried me and sprinkled water on my grave, stand by my grave, face the qiblah and supplicate for me."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 3158