﴿ ٱلَّذِينَ ءَاتَيْنَٰهُمُ ٱلْكِتَٰبَ يَعْرِفُونَهُۥ كَمَا يَعْرِفُونَ أَبْنَآءَهُمُ ۘ ٱلَّذِينَ خَسِرُوٓا۟ أَنفُسَهُمْ فَهُمْ لَا يُؤْمِنُونَ ﴾

“They unto whom we have vouchsafed revelation aforetime know this as they know their own children; yet those [of them] who have squandered their own selves -it is they who refuse to believe.”

Please check ayah 6:21 for complete tafsir.