That the Prophet marked his Budn on the right side and the blood flowed down and marked it. (Using translation from Nasāʾī 2773)
أَنَّ رَسُولَ اللهِ ﷺ أَشْعَرَ بَدَنَتَهُ مِنَ الجَانِبِ الْأَيْمَنِ ثُمَّ سَلَتَ الدَّمَ عَنْهَا وَقَلَّدَهَا نَعْلَيْنِ