Surah At-Tawbah — Ayah 43 (9:43)
عَفَا ٱللَّهُ عَنكَ لِمَ أَذِنتَ لَهُمۡ حَتَّىٰ يَتَبَيَّنَ لَكَ ٱلَّذِينَ صَدَقُواْ وَتَعۡلَمَ ٱلۡكَٰذِبِينَ ٤٣
English translation (Saheeh International)
Allāh has pardoned you, [O Muḥammad, but] why did you give them permission [to remain behind]? [You should not have] until it was evident to you who were truthful and you knew [who were] the liars.
Brief commentary
May Allah forgive the Messenger for his decision to permit them to stay behind! Why did he do so before it became apparent to him who had real excuses and who was lying? Then he could have excused those who were telling the truth, not those who were lying.