The one who gives an oath regarding something although he has not been asked to give an oath

Sahih al-Bukhari · Book 83 · Hadith 6651

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 …

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. After…