Quran 48:16 from Surah Al-Fath on Divine Marvels.
قُل لِّلۡمُخَلَّفِينَ مِنَ ٱلۡأَعۡرَابِ سَتُدۡعَوۡنَ إِلَىٰ قَوۡمٍ أُوْلِي بَأۡسٖ شَدِيدٖ تُقَٰتِلُونَهُمۡ أَوۡ يُسۡلِمُونَۖ فَإِن تُطِيعُواْ يُؤۡتِكُمُ ٱللَّهُ أَجۡرًا حَسَنٗاۖ وَإِن تَتَوَلَّوۡاْ كَمَا تَوَلَّيۡتُم مِّن قَبۡلُ يُعَذِّبۡكُمۡ عَذَابًا أَلِيمٗا
English translation: Say to those who remained behind of the Bedouins You will be called to a people possessors of military might possessors of military might great you will fight them or they will submit Then if you obey Allah will give you Allah will give you a reward good but if you turn away as you turned away before before He will punish you (with) a punishment painful
Transliteration: qul lil'mukhallafina mina al-a'rabi satud'awna ila qawmin uli basin shadidin tuqatilunahum aw yus'limuna fa-in tuti'u yu'tikumu al-lahu ajran hasanan wa-in tatawallaw kama tawallaytum min qablu yu'adhib'kum adhaban aliman