The Messenger of Allah ﷺ sent me to my people of Aslam and said, "Instruct your people to fast this day, the day of Ashura. Whoever among them you find has already eaten in the early part of the day, let him fast the remainder of it."
بعثني رسول الله ﷺ إلى قومي من أسلم. فقال: مر قومك فليصوموا هذا اليوم يوم عاشوراء، فمن وجدته منهم قد أكل في أول يومه، فليصم آخره.
Imam Ahmad narrated it (15962), as did Tabarani in Al-Kabir (22/207), and Tahawi in his Mushkil (2275), all of them through the route of Muhammad bin Ishaq, from Abdullah bin Abu Bakr, from Habib bin Hind bin Asma, from his father, and he related it. Its chain is hasan because of Muhammad bin Ishaq, for his narration is hasan when he states his source explicitly, and he did state it explicitly in Ahmad's version. Haythami said in Al-Majmu (3/185), "Ahmad and Tabarani narrated it, and Ahmad's narrators are reliable."However, there is disagreement among historians over the name of the man who was sent, whether he was Hind bin Asma bin Haritha Aslami, who had companionship with the Prophet as Bukhari, Ibn Sakan, and others stated, and who died during the caliphate of Muawiya, or whether he was Hind bin Haritha Aslami, the uncle of Hind bin Asma.Hafiz said in Al-Isaba, in the biography of "Hind bin Asma bin Haritha Aslami," "Ibn Kalbi claimed that the one commanded to do this was Hind bin Haritha, and Abu Umar followed him in this."I say, Hakim likewise narrated it (3/529-530) through another route, from Yahya bin Hind bin Haritha, from his father Hind bin Haritha, that the Prophet ﷺ sent him on the day of Ashura. And he said, "Sahih."However, Imam Ahmad said in his Musnad (15963), "This Hind bin Haritha was one of the companions of Hudaybiya, and his brother, the one whom the Messenger of Allah ﷺ sent to command his people to fast on Ashura, was Asma bin Haritha, for he said that the Messenger of Allah ﷺ sent him and said, 'Command your people to fast this day.' He said, 'What do you think if I find that they have already eaten?' He said, 'Then let them complete the rest of their day.'"He narrated it from Affan, who said, Wahib narrated to us, Abdul-Rahman bin Harmala narrated to us, from Yahya bin Hind bin Haritha, and Hind was one of the companions of Hudaybiya... and he related it. Then Yahya bin Hind narrated to me, from Asma bin Haritha, "that the Messenger of Allah ﷺ sent him," and he related the hadith.Bazzar also narrated it through the route of Harmala, in Kashf Astar (1048). No one narrated from Yahya bin Hind bin Haritha except Abdul-Rahman bin Harmala, and Ibn Hibban mentioned him in Al-Thiqat, so he is acceptable according to Hafiz's terminology. And indeed he is, for Ibn Hibban narrated it in his Sahih (3618) through the route of Sahl bin Bakkar, who said, Wahib narrated to us, from Abdul-Rahman bin Harmala, from Saeed bin Musayab, from Asma bin Haritha, that the Messenger of Allah ﷺ sent him to his people, and he related the hadith. This is a strong corroboration supporting Yahya bin Hind bin Haritha.So we must either say that the one sent was Hind bin Asma bin Haritha, or his uncle Hind bin Haritha, or his brother Asma bin Haritha, though the last is unlikely. The correct view is that it was specifically one of them, but the historians did not establish it precisely. The hadith is sahih, and not knowing exactly who was sent does not affect the soundness of the hadith.The scholars have spoken at length in determining the identity of the one sent, and what I have mentioned is the summary of it. Some of them claimed there is confusion in the chain because of this disagreement. But the correct view is that there is no confusion in it, because the one sent was a companion, and not knowing his name does not cause harm, as is well known.