"That they attributed," meaning: because they attributed "a son to the Most Merciful." Qatada said: It has reached us that Ka'b said: The angels became angry, and Hell was fueled up when they said what they said.
﴿ان دعوا﴾ بِأَن دعوا ﴿للرحمن ولدا﴾ قَالَ قَتَادَةُ: بَلَغَنَا أَنَّ كَعْبًا قَالَ: غَضِبَتِ الْمَلَائِكَةُ، وَسُعِّرَتْ جَهَنَّمُ حِين قَالُوا مَا قَالُوا.
