The Prophet ﷺ said, "Whoever cheats us is not one of us."
أن النبي ﷺ قال: من غشنا فليس منا.
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Bazzar narrated it -Kashf Astar (1256)- from Amr bin Ali and Bishr bin Adam, who said, Abu Ali Hanafi told us, Harun Shami told us, from Hakam, from Ibrahim, from Aswad, from Ayesha, and he related it. Its isnad is hasan because of Harun Shami, whom I was not able to identify precisely, but Haythami said in al-Majmu (2/87), "Bazzar narrated it and its narrators are trustworthy," so perhaps he identified him. Ibn Hajar also said in Mukhtasar Zawaid Bazzar (879), "Its narrators are trustworthy."On this topic there is also a report from Ibn Umar, who said, the Messenger of Allah ﷺ passed by some food whose seller had made it look attractive, so he put his hand into it and found that the food underneath was of poor quality. He said, "Sell this separately and that separately. Whoever deceives us is not one of us." Ahmad narrated it (5113), and Bazzar -Kashf Astar (1255)-, and Tabarani in al-Awsat (2511), all of them through the hadith of Abu Mashar, from Nafi, from Ibn Umar, and he related it. Abu Mashar's name is Najeeh bin Abdul-Rahman Sindi, and he is daif.On this topic there is also what was narrated from Abu Humra, who said, I saw the Messenger of Allah ﷺ pass by the side of a man who had food in a container, so he put his hand into it. He said, "It seems you have practiced deception. Whoever deceives us is not one of us." Ibn Majah narrated it (2225) from Abu Bakr bin Abu Shayba, who said, Abu Naeem told us, who said, Yunus bin Abu Ishaq told us, from Abu Dawud, from Abu Humra, and he related it. Qudai also narrated it in Musnad Shihab (353) through another path from Abu Naeem. Abu Dawud is Nufay bin Harith al-Amaa, known by his kunya. Ibn Main called him a liar. Nasai said, "Discarded." Ibn Hibban said, "He narrates fabricated material from trustworthy narrators, believing it to be genuine. It is not permissible to rely on him or narrate from him except by way of using him for corroboration" (al-Majruhin 1/116). He also mentioned him in al-Thiqat (5/284). Bukhari said, "Abu Humra was a companion, but this hadith of his is not sahih, and he is the sole narrator of this hadith."On this topic there is also what was narrated from Abu Burda bin Niyar, who said, I went along with the Prophet ﷺ to Baqi al-Musalla. He put his hand into some food, then withdrew it, and found that it was adulterated or mixed. He said, "Whoever deceives us is not one of us." Ahmad narrated it (15833), and Bazzar -Kashf Astar (99)-, and Tabarani in al-Kabir (22/521), all of them through the route of Sharik, from Abdullah bin Isa, from Jamee bin Umayr, from his maternal uncle Abu Burda bin Niyar, and he related it. Its isnad is daif because of Jamee bin Umayr Tamimi Abu Aswad. Bukhari said, "There is something questionable about him." Ibn Hibban said, "He was a Rafidi who fabricated hadith." Abu Hatim, however, said, "His standing is one of truthfulness." The correct view is that he is extremely daif, for he was a fanatical Shiite Rafidi, and Sharik is Ibn Abdullah Nakhai, who had poor memory. However, he was corroborated. Tabarani narrated it in al-Awsat (4/293), and Daraqutni in al-Ilal (6/24-25), from Qays bin Rabi, from Abdullah bin Isa, from Saeed bin Abu Burda, from his paternal uncle Abu Burda, differing from him on two points, one in saying Jamee bin Umayr, and the other in saying "from his maternal uncle." Ibn Hajar concluded in al-Isabah that Abu Burda bin Niyar was the paternal uncle of Saeed bin Umayr bin Niyar, so the error lies with Sharik, since he had poor memory, as already mentioned.On this topic there is also a report from Abdullah bin Masud, as a saying of the Prophet, "Whoever deceives us is not one of us, and cunning and deception belong in the Fire." Tabarani narrated it in al-Kabir (10/138) and al-Saghir (1/261), and Abu Naeem in al-Hilya (4/189), and Ibn Hibban in his Sahih (567), and Qudai in Musnad Shihab (253, 354), all of them through the route of Fadl bin Hubab, who said, Uthman bin Haytham bin Jahm told us, who said, my father told me, from Aasim, from Zirr, from Abdullah, and he related it. Abu Naeem said, "It is unusual as a hadith of Aasim. Uthman alone transmitted it, and we have recorded it only from the hadith of Fadl bin Hubab." I say, its flaw lies with Uthman bin Haytham, for despite his truthfulness, his memory deteriorated and he came to simply repeat whatever he was told. Fadl bin Hubab, who narrated from him, heard from him after this deterioration had occurred. His father, Haytham bin Jahm, was narrated from only by his son Uthman, and no one confirmed him as trustworthy, so he is unknown. As for what Abu Hatim said about him, as found in al-Jarh wal-Tadeel (9/83), "I have not seen anything objectionable in his hadith," this is not an affirmation of his trustworthiness. It only indicates that what he narrates agrees with the hadith of others. Not everyone who narrates a hadith that agrees with others is necessarily trustworthy, for he may err in attributing the hadith to someone other than its actual source.On this topic there are other hadiths that are not sound. Only what we have mentioned is sahih.As for his saying ﷺ, "Whoever deceives us is not one of us," its meaning is that such a person is not following our way and our guidance, which consists of truthfulness and fidelity. As for those who interpret it to mean that such a person has left our religion, that is a mistake. As for what has been reported from Sufyan Thawri, that he disliked the interpretation of "is not one of us" as "is not like us," as mentioned by Abu Dawud (3/732), his intention was to leave the statement as it is, so that it would have greater impact on the hearts and be more forceful as a deterrent, not that he considered such a person to be an unbeliever or excluded from the religion.