Mishkat al-Masabih #3296

Ibn ‘Abbas said: While the Prophet was preaching a man was standing, so he asked about him and was told that he was Abu Isra’il who had taken a vow to stand and not to sit, or go into the shade, or speak, but to fast. Thereupon the Prophet said, “Command him to speak, go into the shade, sit and complete his fast.” Bukhari transmitted it.