﴿ وَإِذَا قَرَأْتَ ٱلْقُرْءَانَ جَعَلْنَا بَيْنَكَ وَبَيْنَ ٱلَّذِينَ لَا يُؤْمِنُونَ بِٱلْءَاخِرَةِ حِجَابًۭا مَّسْتُورًۭا ﴾

“But [thus it is:] whenever thou recitest the Qur'an, We place an invisible barrier between thee and those who will not believe in the life to come: -”

(And when thou recitest the Qur'an) in Mecca (We place between thee, and those who believe not in the Hereafter) those who do not believe in resurrection after death, meaning: Abu Jahl and his host (a hidden barrier) a veiled barrier.