Fussilat - 41:14

إِذْ جَاءتْهُمُ الرُّسُلُ مِن بَيْنِ أَيْدِيهِمْ وَمِنْ خَلْفِهِمْ أَلَّا تَعْبُدُوا إِلَّا اللَّهَ قَالُوا لَوْ شَاء رَبُّنَا لَأَنزَلَ مَلَائِكَةً فَإِنَّا بِمَا أُرْسِلْتُمْ بِهِ كَافِرُونَ
[41:14]
When their messengers came to them from before them and from behind them, saying, Serve nothing but Allah, they said: If our Lord had pleased He would certainly have sent down angels, so we are surely unbelievers in that with which you are sent.
Behold, the messengers came to them, from before them and behind them, (preaching): "Serve none but Allah." They said, "If our Lord had so pleased, He would certainly have sent down angels (to preach). Now we reject your mission (altogether)."
When their messengers came unto them from before them and behind them, saying: Worship none but Allah! they said: If our Lord had willed, He surely would have sent down angels (unto us), so lo! we are disbelievers in that wherewith ye have been sent.