Surah At-Tawbah 9:43
عَفَا ٱللَّهُ عَنكَ لِمَ أَذِنتَ لَهُمْ حَتَّىٰ يَتَبَيَّنَ لَكَ ٱلَّذِينَ صَدَقُوا۟ وَتَعْلَمَ ٱلْكَٰذِبِينَ ٤٣
EnglishSahih International
May Allah pardon you, [O Muhammad]; 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.