"[Those] who assume [i.e., know] that they will meet their Lord."
Muhammad said: In the speech of the Arabs, 'zann' (assumption/thought) has two meanings: doubt and certainty. Durayd ibn al-Simma said:
(I said to them: 'Assume [know] with two thousand fighters... their elite, in Persian chainmail.')
The meaning of 'zannu' (they assumed/thought) here is: they were certain.
﴿الَّذين يظنون﴾ [يعلمُونَ] ﴿إِنَّهُم ملاقوا رَبهم﴾.
قَالَ مُحَمَّد: الظَّن فِي كَلَام الْعَرَب بمعنيين: شكّ ويقين؛ قَالَ دُرَيْد بن الصمَّة:
(فَقلت لَهُم ظنُّوا بألفي مقَاتل … سراتهم بالفارسي المسرد)
وَمعنى ظنُّوا: أَي: أيقنوا.
