Surah At-Tawba, Verse 43
عَفَا ٱللَّهُ عَنكَ لِمَ أَذِنتَ لَهُمْ حَتَّىٰ يَتَبَيَّنَ لَكَ ٱلَّذِينَ صَدَقُوا۟ وَتَعْلَمَ ٱلْكَٰذِبِينَ
Translation — Sahih 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.
Source
Kur'an-ı Kerim, Tevbe Suresi 9:43
https://kuran.diyanet.gov.tr/mushaf/kuran-meal-2/9-suresi-43-ayet