The one who gives an oath regarding something although he has not been asked to give an oath
حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا اللَّيْثُ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم اصْطَنَعَ خَاتَمًا مِنْ ذَهَبٍ وَكَانَ يَلْبَسُهُ، فَيَجْعَلُ فَصَّهُ فِي بَاطِنِ كَفِّهِ، فَصَنَعَ النَّاسُ خَوَاتِيمَ ثُمَّ إِنَّهُ جَلَسَ عَلَى الْمِنْبَرِ فَنَزَعَهُ، فَقَالَ " إِنِّي كُنْتُ أَلْبَسُ هَذَا الْخَاتِمَ وَأَجْعَلُ فَصَّهُ مِنْ دَاخِلٍ ". فَرَمَى بِهِ ثُمَّ قَالَ " وَاللَّهِ لاَ أَلْبَسُهُ أَبَدًا ". فَنَبَذَ النَّاسُ خَوَاتِيمَهُمْ.
Narrated Ibn `Umar: Allah's Messenger (ﷺ) had a gold ring made for himself, and he used to wear it with the stone towards the inner part of his hand. Consequently, the people had similar rings made for themselves. Afterwards the Prophet; sat on the pulpit and took it off, saying, "I used to wear this ring and keep its stone towards the palm of my hand." He then threw it away and said, "By Allah, I will never wear it." Therefore all the people threw away their rings as well.