Ahmad 7019

Its isnad is hasan, on account of Muthanna bin Sabbah, as we explained under 6919. Haythami mentioned the hadith in Majma al-Zawaid 1:97, and said, "Ahmad and Tabarani in al-Saghir and al-Awsat narrated it, except that he said, 'It is disbelief in a man.'" It is from the narration of Amr bin Shuayb, from his father, from his grandfather.Ibn Majah narrated its meaning in similar wording, 2:87, by way of Sulayman bin Bilal, from Yahya bin Saeed, from Amr bin Shuayb, from his father, from his grandfather, that the Prophet ﷺ said, "It is disbelief in a man to claim a lineage he does not know, or to deny one, however slight it may be."Its commentator quoted from the additions of Busiri, "This hadith is found in some manuscripts but not others, and Mizzi did not mention it in al-Atraf. Its isnad is sahih." I think it is among the additions of Ibn Qattan, meaning Abul Hasan Ali bin Ibrahim al-Qattan, the transmitter of the Sunan from Ibn Majah. See also 6834.His saying "however slight it may be" means however trivial or insignificant it may be.