"Thus have We sent you to a nation before which other nations have passed away," meaning: just as We sent [messengers] to the nations that had passed away before this nation. "While they disbelieve in the Most Merciful," for they used to say: As for Allah, we know Him, but as for the Most Merciful, we do not know Him. "Say, 'He is my Lord; there is no deity except Him. Upon Him I have relied, and to Him is my return,'" meaning: repentance.
﴿كَذَلِكَ أَرْسَلْنَاكَ فِي أُمَّةٍ قَدْ خلت من قبلهَا أُمَم﴾ أَيْ: كَمَا أَرْسَلْنَا فِي الأُمَمِ الَّتِي قَدْ خَلَتْ مَنْ قَبْلِ هَذِهِ الأُمَّةِ ﴿وَهُمْ يَكْفُرُونَ بِالرَّحْمَنِ﴾ كَانُوا يَقُولُونَ: أَمَّا اللَّهُ فَنَعْرِفُهُ، وَأما الرَّحْمَن فَلَا نعرفه ﴿قلا هُوَ رَبِّي لَا إِلَهَ إِلا هُوَ عَلَيْهِ تَوَكَّلْتُ وَإِلَيْهِ مَتَابِ﴾ يَعْنِي: التَّوْبَة.