﴿ عَفَا ٱللَّهُ عَنكَ لِمَ أَذِنتَ لَهُمْ حَتَّىٰ يَتَبَيَّنَ لَكَ ٱلَّذِينَ صَدَقُوا۟ وَتَعْلَمَ ٱلْكَٰذِبِينَ ﴾

“May God pardon thee [O Prophet]! Why didst thou grant them permission [to stay at home] ere it had become obvious to thee as to who was speaking the truth, and [ere] thou camest to know. [who were] the liars?”

The Prophet s exercising his personal judgement had given leave to a group to stay behind and so the following was revealed as a reprimand for him but with the pardon first in order to reassure his heart May God pardon you! Why do you give them leave to stay behind; why did you not leave them until it was clear to you which of them spoke the truth in their excuse and you knew those who were lying in it?