Narrated Ibn 'Abbas:While the Prophet (ﷺ) was preaching a man was standing in the sun. He asked about him. They said: He is Abu Isra'il who has taken a vow to stand and not to sit, or go into shade, or speak, but to fast. Thereupon he said: Command him to speak, to go into the shade, sit and complete his fast.
حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا وُهَيْبٌ، حَدَّثَنَا أَيُّوبُ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ : بَيْنَمَا النَّبِيُّ صلى الله عليه وسلم يَخْطُبُ إِذَا هُوَ بِرَجُلٍ قَائِمٍ فِي الشَّمْسِ فَسَأَلَ عَنْهُ قَالُوا : هَذَا أَبُو إِسْرَائِيلَ نَذَرَ أَنْ يَقُومَ وَلاَ يَقْعُدَ، وَلاَ يَسْتَظِلَّ وَلاَ يَتَكَلَّمَ وَيَصُومَ . قَالَ : " مُرُوهُ فَلْيَتَكَلَّمْ وَلْيَسْتَظِلَّ وَلْيَقْعُدْ، وَلْيُتِمَّ صَوْمَهُ " .
AbuDaud
Oaths and Vows (Kitab Al-Aiman Wa Al-Nudhur) • Hadith 3300