(31) باب النَّذْرِ فِيمَا لاَ يَمْلِكُ وَفِي مَعْصِيَةٍ
Narrated Ibn `Abbas:
While the Prophet (ﷺ) was delivering a sermon, he saw a man standing, so he asked about that man. They (the people) said, "It is Abu Israil who has vowed that he will stand and never sit down, and he will never come in the shade, nor speak to anybody, and will fast.'' The Prophet (ﷺ) said, "Order him to speak and let him come in the shade, and make him sit down, but let him complete his fast."
Reference: Sahih al-Bukhari 6704
In-book reference: Book 83, Hadith 81
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 8, Book 78, Hadith 695