That the Prophet passed by while he was circumambulating the Kabah with a man who was leading another with a ring in his nose. The Messenger of Allah stopped him with his hand then told him to lead him by his hand.  

أَنَّ النَّبِيَّ ﷺ مَرَّ وَهُوَ يَطُوفُ بِالْكَعْبَةِ بِإِنْسَانٍ يَقُودُهُ إِنْسَانٌ بِخِزَامَةٍ فِي أَنْفِهِ فَقَطَعَهُ النَّبِيُّ ﷺ بِيَدِهِ ثُمَّ أَمَرَهُ أَنْ يَقُودَهُ بِيَدِهِ  

"The Messenger of Allab passed by a man who was leading another man with something that he had stipulated in a vow. The Prophet took it and broke it, and he said: 'It is a vow.'" (Sahih) Chatper 136. It Is Permissible To Speak During Tawaf  

مَرَّ رَسُولُ اللَّهِ ﷺ بِرَجُلٍ يَقُودُهُ رَجُلٌ بِشَىْءٍ ذَكَرَهُ فِي نَذْرٍ فَتَنَاوَلَهُ النَّبِيُّ ﷺ فَقَطَعَهُ قَالَ إِنَّهُ نَذْرٌ