Al-Fath - 48:16

قُل لِّلْمُخَلَّفِينَ مِنَ الْأَعْرَابِ سَتُدْعَوْنَ إِلَى قَوْمٍ أُوْلِي بَأْسٍ شَدِيدٍ تُقَاتِلُونَهُمْ أَوْ يُسْلِمُونَ فَإِن تُطِيعُوا يُؤْتِكُمُ اللَّهُ أَجْرًا حَسَنًا وَإِن تَتَوَلَّوْا كَمَا تَوَلَّيْتُم مِّن قَبْلُ يُعَذِّبْكُمْ عَذَابًا أَلِيمًا
[48:16]
Say to those of the dwellers of the desert who were left behind: You shall soon be invited (to fight) against a people possessing mighty prowess; you will fight against them until they submit; then if you obey, Allah will grant you a good reward; and if you turn back as you turned back before, He will punish you with a painful punishment.
Say to the desert Arabs who lagged behind: "Ye shall be summoned (to fight) against a people given to vehement war: then shall ye fight, or they shall submit. Then if ye show obedience, Allah will grant you a goodly reward, but if ye turn back as ye did before, He will punish you with a grievous Penalty."
Say unto those of the wandering Arabs who were left behind: Ye will be called against a folk of mighty prowess, to fight them until they surrender; and if ye obey, Allah will give you a fair reward; but if ye turn away as ye did turn away before, He will punish you with a painful doom.