"when i came to najran, they (the christians of najran) asked me: you read " o sister of aaron " in the qur'an, whereas moses was born much before jesus. when i came back to the prophet i asked him about that, he said: the (people of the old age) used to give names (to their children) after the names of apostles and pious persons who had gone before them" meaning that aaron here was not moses' brother but another one. al-baghawi also cites a narration from al-kalbi that aaron referred to here was a brother of maryam through her father, and he was the most righteous man amongst children of israel in that time.