When Uthman ibn Maz'un died, he was brought out on his bier and buried. The Prophet ﷺ ordered a man to bring him a stone, but he was unable to carry it. The Messenger of Allah ﷺ got up and going over to it rolled up his sleeves. The narrator Kathir told that al-Muttalib remarked: The one who told me about the Messenger of Allah ﷺ said: I still seem to see the whiteness of the forearms of the Messenger of Allah ﷺ when he rolled up his sleeves. He then carried it and placed it at his head saying: I am marking my brother's grave with it, and I shall bury beside him those of my family who die. (Using translation from Abū Dāʾūd 3206)   

لَمَّا مَاتَ عُثْمَانُ بْنُ مَظْعُونٍ أُخْرِجَ بِجِنَازَتِهِ فَدُفِنَ أَمَرَ النَّبِيُّ ﷺ رَجُلًا أَنْ يَأْتِيَهُ بِحَجَرٍ فَلَمْ يَسْتَطِعْ حَمْلَهُ فَقَامَ إِلَيْهَا رَسُولُ اللهِ ﷺ وَحَسَرَ عَنْ ذِرَاعَيْهِ قَالَ كَثِيرٌ قَالَ الْمُطَّلِبُ قَالَ الَّذِي يُخْبِرُنِي ذَلِكَ عَنْ رَسُولِ اللهِ ﷺ كَأَنِّي أَنْظُرُ إِلَى بَيَاضِ ذِرَاعَيْ رَسُولِ اللهِ ﷺ حِينَ حَسَرَ عَنْهَا ثُمَّ حَمَلَهَا فَوَضَعَهَا عِنْدَ رَأْسِهِ وَقَالَ لِيُعْلَمَ بِهَا قَبْرُ أَخِي وَأَدْفِنَ إِلَيْهِ مَنْ مَاتَ مِنْ أَهْلِي