 The majority of Sayyid believe they are one of the modern day descendants of Muhammad , and that they are therefore the descendants of Ishmael and his second son Qedar . Abu Ja 'far al @-@ Baqir ( 676 – 743 CE ) wrote that his father Ali ibn Husayn informed him that Mohammed had said : " The first whose tongue spoke in clear Arabic was Ishmael , when he was fourteen years old . " Hisham Ibn Muhammad al @-@ Kalbi ( 737 – 819 CE ) established a genealogical link between Ishmael and Mohammed using writings that drew on biblical and Palmyran sources , and the ancient oral traditions of the Arabs . His book , Jamharat al @-@ Nasab ( " The Abundance of Kinship " ) , seems to posit that the people known as " Arabs " are all descendants of Ishmael . Ibn Kathir ( 1301 – 1373 ) writes , " All the Arabs of the Hijaz are descendants of Nebaioth and Qedar . " Medieval Jewish sources also usually identified Qedar with Arabs and / or Muslims . According to author and scholar Irfan Shahîd , Western scholars viewed this kind of " genealogical Ishmaelism " with suspicion , seeing it as , 
