Sahih al-Bukhari 6706
Narrated Ziyad bin Jubair:
I was with Ibn `Umar when a man asked him, "I have vowed to fast every Tuesday or Wednesday 
throughout my life and if the day of my fasting coincided with the day of Nahr (the first day of `Id-al- 
Adha), (What shall I do?)" Ibn `Umar said, "Allah has ordered the vows to be fulfilled, and we are 
forbidden to fast on the day of Nahr." The man repeated his question and Ibn `Umar repeated his 
former answer, adding nothing more.
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مَسْلَمَةَ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، عَنْ يُونُسَ، عَنْ زِيَادِ بْنِ جُبَيْرٍ، قَالَ كُنْتُ مَعَ ابْنِ عُمَرَ فَسَأَلَهُ رَجُلٌ فَقَالَ نَذَرْتُ أَنْ أَصُومَ كُلَّ يَوْمِ ثَلاَثَاءَ أَوْ أَرْبِعَاءَ مَا عِشْتُ، فَوَافَقْتُ هَذَا الْيَوْمَ يَوْمَ النَّحْرِ‏.‏ فَقَالَ أَمَرَ اللَّهُ بِوَفَاءِ النَّذْرِ، وَنُهِينَا أَنْ نَصُومَ يَوْمَ النَّحْرِ‏.‏ فَأَعَادَ عَلَيْهِ فَقَالَ مِثْلَهُ، لاَ يَزِيدُ عَلَيْهِ‏.‏