That is because they said to those who disliked what Allah sent down, "We will obey you in part of the matter." And Allah knows what they conceal.
The Saheeh International Quran Translation
ذَٰلِكَ بِأَنَّهُمْ قَالُوا۟ لِلَّذِينَ كَرِهُوا۟ مَا نَزَّلَ ٱللَّهُ سَنُطِيعُكُمْ فِى بَعْضِ ٱلْأَمْرِ وَٱللَّهُ يَعْلَمُ إِسْرَارَهُمْThat is because they said to those who disliked what Allah sent down, "We will obey you in part of the matter." And Allah knows what they conceal.