(Al-Muaminoon) 23 : 23
وَلَقَدْ أَرْسَلْنَا نُوحًا إِلَىٰ قَوْمِهِ فَقَالَ يَا قَوْمِ اعْبُدُوا اللَّهَ مَا لَكُمْ مِنْ إِلَٰهٍ غَيْرُهُ ۖ أَفَلَا تَتَّقُونَ
And surely, We had sent Noah to his people, and he said: "Oh my people, you serve Lord Allah, you have no deity besides Him; then will you not be heedful?"
See explanation 1: 4; 11: 2-3; 21: 24-25 and 108.