The Prophet ﷺ said, "Whoever is overcome by vomiting is not required to make up the fast, but whoever induces vomiting deliberately must make it up."
أن النبي ﷺ قال: من ذرعه القيء فليس عليه قضاء، ومن استقاء عمدا فليقض.
It has two paths from Hisham bin Hassan, from Muhammad bin Sirin, from Abu Hurairah. The first is through Isa bin Yunus, from him. Abu Dawud (2380), Tirmidhi (720), Ibn Majah (1676), Daraqutni (2273), and Bayhaqi (4/219) narrated it through this path, and Ibn Khuzayma (1960) and Hakim (1/427) graded it sahih. Daraqutni said, "All its narrators are trustworthy." Hakim said, "Sahih according to the criteria of the two sheikhs." However, Tirmidhi reported from Bukhari that he said, "I do not consider it preserved." Tirmidhi himself said, this is a hasan gharib hadith, we do not know it from the hadith of Hisham, from Ibn Sirin, from Abu Hurairah, from the Prophet ﷺ, except through the hadith of Isa bin Yunus. He said, "This hadith has been narrated through other routes, from Abu Hurairah, from the Prophet ﷺ, but its chain is not sound." End of quote.Bayhaqi said, Hisham bin Hassan Qurdusi narrated it alone. He said, some of the memorizers do not consider it preserved (he probably means Bukhari by this). He said, Abu Dawud said, I heard Ahmad bin Hanbal say, "There is nothing to this." I say, as for Hisham bin Hassan Qurdusi Azdi narrating it alone, this does not harm it, for he is trustworthy. Hafiz said in Taqrib, "Trustworthy, one of the most reliable people regarding Ibn Sirin," and this is one of his narrations. As for Isa bin Yunus, he is the son of Abu Ishaq Sabi, and he is "trustworthy and reliable." Moreover, he did not narrate it alone as Tirmidhi claimed, rather he was corroborated, as follows.The second path is what Hafs bin Ghiyath narrated, from Hisham bin Hassan. Ibn Majah, Ibn Khuzayma (1961), Hakim, and Bayhaqi narrated it through this path, and Abu Dawud alluded to it. Hakim said, Isa bin Yunus corroborated him (meaning he corroborated Hafs bin Ghiyath). Bukhari, may Allah have mercy on him, did not include this hadith in his Sahih, but he criticized it in a statement he made, as he mentioned in his Sahih, in the chapter on cupping and vomiting for the fasting person, "Yahya bin Salih told me, Muawiya bin Salam narrated to us, Yahya narrated to us from Umar bin Hakam bin Thawban, who heard Abu Hurairah say, 'If he vomits, he does not break his fast, for it is something that comes out, not something that enters.' It is also reported from Abu Hurairah that he broke his fast in that case, but the first report is more sound."Tirmidhi reported from him in Ilal al-Kabir (1/343), "I asked Muhammad about this hadith, and he did not know it except through the hadith of Isa bin Yunus, from Hisham bin Hassan, from Ibn Sirin, from Abu Hurairah. He said, I do not consider it preserved. Yahya bin Abu Kathir narrated from Umar bin Hakam that Abu Hurairah did not consider vomiting to break the fast of the fasting person." End of quote.I say, what Bukhari said in Tarikh al-Kabir (1/91-92) is, Musaddad told me, Isa bin Yunus narrated to us from Hisham, from Ibn Sirin, from Abu Hurairah, from the Prophet ﷺ, who said, "Whoever deliberately induces vomiting must make up the fast." He said, this is not sound, rather this is narrated from Abdullah bin Saeed, from his father, from Abu Hurairah, as a raised hadith. Yahya bin Salih differed from him, saying, Muawiya narrated to us, saying, Yahya narrated to us, from Umar bin Hakam bin Thawban, who heard Abu Hurairah say, "If one of you vomits, he does not break his fast, for it is something that comes out, not something that enters."It is understood from Bukhari's statement that he is comparing the narration of Abdullah bin Saeed, from his father, from Abu Hurairah, as a raised hadith, with what Yahya bin Salih narrated, from Muawiya, from the words of Abu Hurairah. There is no doubt that the raised narration of Abdullah bin Saeed is daif due to the weakness of Abdullah bin Saeed, for the scholars unanimously agree on grading him as daif. This is why the authors of the sahih collections such as Ibn Khuzayma and Hakim, and the authors of the sunan works, avoided narrating this hadith through the path of Abdullah bin Saeed, and instead narrated it through the path of Isa bin Yunus and Hafs bin Ghiyath with their chains.Daraqutni, who is a leading authority in critical evaluation, stated explicitly that all its narrators are trustworthy. As for what Isa bin Yunus and Hafs bin Ghiyath narrated, the first part of it, namely his saying, "Whoever is overcome by vomiting need not make up the fast," agrees with the fatwa of Abu Hurairah, so there is no contradiction between what he narrated and what he gave as a legal opinion. As for his saying, "Whoever deliberately induces vomiting must make up the fast," this is something on which his fatwa is silent.Since it was narrated by two trustworthy and reliable memorizers, with no contradicting narration, it is sahih according to the rules of hadith science, since there is no hidden defect in it and no anomaly. That is why many of the memorizers graded it sahih. Nawawi said in Majmu (6/316), "The conclusion is that the hadith of Abu Hurairah, by the totality of its paths and the corroborating narrations mentioned, is a hasan hadith. Likewise, more than one of the memorizers have explicitly stated it to be hasan. The fact that Hisham bin Hassan narrated it alone does not harm it, for he is trustworthy, and an addition by a trustworthy narrator is accepted by the majority of the people of hadith, jurisprudence, and legal theory."Tirmidhi said, following the hadith of Abu Hurairah, "The practice among the people of knowledge is in accordance with the hadith of Abu Hurairah from the Prophet ﷺ, that if the fasting person is overcome by vomiting, he owes no makeup fast, but if he deliberately induces vomiting, he must make it up. This is the view held by Sufyan Thawri, Shafii, Ahmad, and Ishaq."