Abū Mūsā (may Allah be pleased with him) reported: “The Jews used to regard the Day of ʿĀshūrāʾ as a festival, so the Prophet (Allah bless and grant him peace) said, ‘Then you should fast on it.’” Agreed upon. This is the wording of al-Bukhārī, while Muslim records: “The Jews venerate it and treat it as a festival.” In another of Muslim’s versions: “The people of Khaybar would fast the Day of ʿĀshūrāʾ and observe it as a festival, dressing their women in jewelry and fine adornment.”
Al-Zuhrī narrated from ʿUbayd Allāh ibn ʿAbd Allāh ibn ʿUtbah, from Ibn ʿAbbās (may Allah be pleased with them both), who said: “The People of the Book used to let their hair hang loose, whereas the idolaters would part theirs. The Messenger of Allah (Allah bless and grant him peace) liked to agree with the People of the Book in matters concerning which he had received no command, so he let the front of his hair fall forward; later on he began to part it.” Agreed upon.
(1) Ṣaḥīḥ al-Bukhārī, same book and chapter as above, Fatḥ al-Bārī, 4/244, ḥadīth no. 2005.
(2) The printed edition reverses the order, reading: “This is Muslim’s wording, and al-Bukhārī’s wording …,” whereas the correct sequence is what I have given, as confirmed by all manuscript copies and by the texts of both al-Bukhārī and Muslim.
(3) Ṣaḥīḥ Muslim, Book of Fasting, chapter “Fasting on the Day of ʿĀshūrāʾ,” 2/796, ḥadīth no. 1131.
(4) Ibid., continuation of the same ḥadīth, 2/796.
(5) ʿUbayd Allāh b. ʿAbd Allāh b. ʿUtbah b. Masʿūd al-Hudhalī, Abū ʿAbd Allāh: a Madinan jurist and firmly reliable narrator of the third generation; all six canonical collections and others transmit from him. He died in 94 AH. See Taqrīb al-Tahdhīb, 1/535, no. 1469 (ʿayn).
(6) Ṣaḥīḥ al-Bukhārī, Book of Dress, chapter “Parting the hair,” Fatḥ al-Bārī, 10/361, ḥadīth no. 5917; and Ṣaḥīḥ Muslim, Book of Virtues, chapter “On the Prophet’s—peace and blessings upon him and his family—wearing his hair loose and parting it,” 4/1816, ḥadīth no. 2336.