وَيَوْمَ نَحْشُرُهُمْ جَمِيعًا ثُمَّ نَقُولُ لِلَّذِينَ أَشْرَكُوٓا۟ أَيْنَ شُرَكَآؤُكُمُ ٱلَّذِينَ كُنتُمْ تَزْعُمُونَ
10:29.
Commentary:
The verb تزعمون (you used to assert) has always been used in the Quran with regard to falsehood. It signifies an assertion of which one is not sure. Thus کنتم تزعمون (you used to assert) would mean, "you asserted with your tongues, while you had doubts in your minds".