وَقَدْ كَفَرُوا۟ بِهِۦ مِن قَبْلُ ۖ وَيَقْذِفُونَ بِٱلْغَيْبِ مِن مَّكَانٍۭ بَعِيدٍ
Commentary:
The verse means to say that disbelievers are making foolish conjectures about the failure of the Prophet’s mission. These conjectures being far removed from the source of "the unseen" or from reality, reason and truth are quite foolish and baseless.