Surah Al-Baqarah 2:204

وَمِنَ ٱلنَّاسِ مَن يُعْجِبُكَ قَوْلُهُۥ فِى ٱلْحَيَوٰةِ ٱلدُّنْيَا وَيُشْهِدُ ٱللَّهَ عَلَىٰ مَا فِى قَلْبِهِۦ وَهُوَ أَلَدُّ ٱلْخِصَامِ

And of the people is he whose speech pleases you in worldly life, and he calls Allāh to witness as to what is in his heart, yet he is the fiercest of opponents.

Translation: Saheeh International

Tafsir

And among people there is he whose speech in the life of this world pleases you but it would not please you in the Hereafter because it contradicts what he actually used to believe; and who calls on God to witness what is in his heart as being in accordance with what he says; …

Excerpt from Tafsir al-Jalalayn, commentary on 2:204, via Quran.com. The reader has the full commentary and 9 more tafsirs.