"So withdraw from them, on the day when the Caller will call to a thing, an unknown (nukr)," meaning: great/grave. And the 'Caller' is the one who will blow the Trumpet.
Muhammad said: "Yad'u" (He will call) was written with the omission of the wāw, in accordance with what occurs in pronunciation, due to the meeting of two quiescent (sākin) letters: the wāw of "yad'ū" and the lām of "al-dā'i." Regarding his statement: "Nukr," with both a damma on the kāf and an unvoweled (sākin) kāf, for "al-nukr" and "al-munkar" are one and the same.
﴿فَتَوَلَّ عَنْهُمْ يَوْمَ يَدْعُ الدَّاعِي إِلَى شَيْءٍ نُّكُرٍ﴾ عَظِيم، والداع هُوَ صَاحب الصُّور.
قَالَ مُحَمَّد: ﴿يدع﴾ كتب بِحَذْف الْوَاو على مَا يجْرِي فِي اللَّفْظ لالتقاء الساكنين الْوَاو من (يَدْعُو) وَاللَّام من (الداع) وَقَوله: (نكر) بِضَم الْكَاف وإسكانها، والنكر وَالْمُنكر واحدٌ.
