Ibn ‘Abbas said, “Once while the Prophet, may Allah bless him and grant him peace, was speaking, a man remained standing, and he asked about him. They said, ‘It is Abu Isra’il who vowed to stand in the sun and not sit down nor seek shade nor speak and to fast.’ The Prophet said, ‘Command him to speak, to seek shade and to sit down but he should complete his fast.'” [al-Bukhari]
