The Messenger of Allah ﷺ was on a journey when he saw a crowd gathered around a man who was being shaded. He asked, "What is this?"They replied, "He is fasting."He said, "It is not righteousness to fast while traveling."
كان رسول الله ﷺ في سفر، فرأى زحاما ورجلا قد ظلل عليه، فقال: ما هذا؟ فقالوا: صائم. فقال: ليس من البر الصوم في السفر.
Bukhari narrated it in "Fasting" (1946), and Muslim in "Fasting" (1115), both through the route of Shuba, who said, "Muhammad bin Abdul-Rahman Ansari narrated to us, he said, 'I heard Muhammad bin Amr bin Hasan bin Ali,'" from Jabir bin Abdullah, and he related it.Muslim added in one narration, Shuba said, "It used to reach me concerning Yahya bin Abu Kathir that he used to add to this hadith, and to this chain, that he said, 'Take the concession that Allah has granted you.'" He said, "But when I asked him about it, he did not remember it."His statement, "when I asked him," means when I asked Muhammad bin Abdul-Rahman Ansari, who is Shuba's teacher, and he did not remember it, but someone else did remember it.The detail of that, as Ibn Qattan explained, is that this hadith is narrated from Jabir by two men, each of whom is named Muhammad bin Abdul-Rahman, namely Ibn Zurara Ansari and Muhammad bin Abdul-Rahman bin Thawban, and Yahya bin Abu Kathir narrated from each of them. One of them is Ibn Thawban, and the other is Ibn Saad bin Zurara. Ibn Thawban heard it directly from Jabir, while Ibn Saad bin Zurara narrated it through an intermediary, Muhammad bin Amr bin Hasan, and this is the narration of the Sahihayn. This is stated in Talkhis (2/205).But the matter is not as he said, for Ibn Zurara Ansari narrates it through an intermediary, as is clear from his own wording, and this is the version narrated by the two Shaykhs. Ansari did not remember this addition, but Ibn Thawban did remember it. Nasai (2258) narrated it from Shuayb bin Shuayb, and Tahawi (3135) narrated it through Walid bin Muslim, both of them from Uzai, who said, "Yahya bin Abu Kathir narrated to me, he said, 'Muhammad bin Abdul-Rahman bin Thawban informed me, he said, "Jabir bin Abdullah informed me,"'" and he related the hadith, adding to it, "So take the concession of Allah that He has granted you, and accept it."Walid bin Muslim is known for concealing his sources, but he has been corroborated, and Yahya bin Abu Kathir is trustworthy, though accused of concealing his sources, except that he explicitly said, "narrated to me," which clears him of that suspicion.Firyabi differed from him, narrating from Uzai, who said, "Yahya narrated to us, he said, 'Muhammad bin Abdul-Rahman informed me, he said, "Someone who heard Jabir narrated to me,"'" similarly.So he inserted between Muhammad bin Abdul-Rahman, who is Ansari, and Jabir, a man, namely Muhammad bin Amr bin Hasan.His word "similarly" refers to something resembling the hadith of Yahya bin Abu Kathir, but everyone who narrated it from him, from Ansari through an intermediary, did not mention this addition.Nasai narrated it through the route of Ali bin Mubarak, and there was disagreement over it. Uthman bin Umar narrated it from Ali bin Mubarak, from Yahya bin Abu Kathir, from Muhammad bin Abdul-Rahman, from a man, from Jabir, without mentioning this addition.Waki narrated it from Ali bin Mubarak, from Yahya bin Abu Kathir, from Muhammad bin Abdul-Rahman bin Thawban, from Jabir, and he did mention the addition. All these narrations are found in Nasai.What appears to be the case is that Yahya would sometimes narrate it with the addition and other times without it, and his addition is acceptable due to the trustworthiness of those who narrated it from him. Ibn Qattan and others have graded this addition sahih.However, it cannot be said that Muslim recorded this addition, because he presented it in suspended form without a connected chain, so it does not meet his standard.