It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) marked the grave of Sayyiduna Uthman bin Maz'un (may Allah be pleased with him) by placing a stone on it.
Imam al-Tabarani (may Allah have mercy on him) said: "Only Isma'il bin Mirsal narrated this hadith from Imam al-Zuhri (may Allah have mercy on him), and Amr bin Khalaf is alone in narrating it."
This is how it appears, (Amr bin Khalaf), in the Dar al-Haramayn edition, and probably the correct name is (Amr bin Khulayf).
Hadith Referenceالمعجم الأوسط / باب العين / 3886
Hadith Takhrij«أخرجه ابن ماجه فى «سننه» برقم: 1561»