{And they said: Legends of the ancients}, meaning: the narrations of the ancients, {he has had them written down}—Muhammad [has had] 'Abd ibn al-Hadrami and Addas [write them down]—{and they are dictated to him morning and evening}.
Muhammad said: {Legends} is the predicate of an omitted subject. The meaning is: And they said: That which he has brought is the legends of the ancients. The singular of 'asatir' (legends) is 'ustura'.
Surat al-Furqan from (verse 7 to verse 11).
﴿وَقَالُوا أساطير الْأَوَّلين﴾ أَي: أَحَادِيث الْأَوَّلين ﴿اكتتبها﴾ مُحَمَّد بن عبد ابْن الْحَضْرَمِيِّ وَعَدَّاسٍ ﴿فَهِيَ تُمْلَى عَلَيْهِ بكرَة وَأَصِيلا﴾.
قَالَ مُحَمَّد: (أساطير) خبر ابْتِدَاء مَحْذُوف؛ الْمَعْنى: وَقَالُوا: الَّذِي جَاءَ بِهِ أَسَاطِيرُ الْأَوَّلِينَ، وَوَاحِد الأساطير: أسطورة.
سُورَة الْفرْقَان من (آيَة ٧ آيَة ١١).