Surah Aali Imran (The Family of Imran), Verse 166

وَمَاۤ اَصَابَكُمْ یَوْمَ الْتَقَی الْجَمْعٰنِ فَبِاِذْنِ اللّٰهِ وَلِیَعْلَمَ الْمُؤْمِنِیْنَ ۟

Wa maa asaabakum yawmal taqal jam'aani fabi iznil laahi wa liya'lamal mu'mineen

“What ye suffered on the day the two armies Met, was with the leave of Allah, in order that He might test the believers,-”

Quran 3:166 (Yusuf Ali Translation)