152 — Ibn ʿAbbās (may Allah be pleased with him) said: While the Prophet (peace and blessings be upon him) was delivering a sermon, he noticed a man standing. He asked about him, and the people replied, “That is Abū Isrāʾīl; he has vowed to stand in the sun and not sit, to seek no shade, to refrain from speaking, and to fast.” The Prophet (peace and blessings be upon him) said, “Tell him to speak, to seek shade, to sit down, and to complete his fast.” Reported by al-Bukhārī.

[Explanation]
The author (may Allah have mercy on him) cites this hadith in the chapter on moderation in worship. A man known as Abū Isrāʾīl had pledged that he would stand in the sun without sitting, remain silent, and fast. While the Prophet (peace and blessings be upon him) was preaching, he saw the man standing in the sun. After inquiring about him and being told his story, the Prophet (peace and blessings be upon him) said, “Tell him to speak, to seek shade, to sit down, and to complete his fast.”

This vow combined matters that are pleasing to Allah, exalted is He, with matters that are not. What is pleasing to Allah is the fast, for fasting is an act of worship, and the Prophet (peace and blessings be upon him) said, “Whoever vows to obey Allah should obey Him.” As for standing in the sun without shade and refraining from speech, these are not things Allah loves. For that reason the Prophet (peace and blessings be upon him) instructed the man to abandon those parts of his vow.

Know that making vows is originally disliked; indeed, some scholars held that it is forbidden and that a person should not make a vow, for by doing so he burdens himself with something that Allah has not obliged him to do.