The Cow
أُو۟لَـٰٓئِكَ ٱلَّذِينَ ٱشْتَرَوُا۟ ٱلضَّلَـٰلَةَ بِٱلْهُدَىٰ فَمَا رَبِحَت تِّجَـٰرَتُهُمْ وَمَا كَانُوا۟ مُهْتَدِينَ
Those are the ones who have purchased error [in exchange] for guidance, so their transaction has brought no profit, nor were they guided.
Nearby ayahs help place verse 2:16 in sequence and meaning.
وَإِذَا لَقُوا۟ ٱلَّذِينَ ءَامَنُوا۟ قَالُوٓا۟ ءَامَنَّا وَإِذَا خَلَوْا۟ إِلَىٰ شَيَـٰطِينِهِمْ قَالُوٓا۟ إِنَّا مَعَكُمْ إِنَّمَا نَحْنُ مُسْتَهْزِءُونَ
And when they meet those who believe, they say, "We believe"; but when they are alone with their evil ones, they say, "Indeed, we are with you; we were only mockers."
ٱللَّهُ يَسْتَهْزِئُ بِهِمْ وَيَمُدُّهُمْ فِى طُغْيَـٰنِهِمْ يَعْمَهُونَ
[But] Allah mocks them and prolongs them in their transgression [while] they wander blindly.
مَثَلُهُمْ كَمَثَلِ ٱلَّذِى ٱسْتَوْقَدَ نَارًا فَلَمَّآ أَضَآءَتْ مَا حَوْلَهُۥ ذَهَبَ ٱللَّهُ بِنُورِهِمْ وَتَرَكَهُمْ فِى ظُلُمَـٰتٍ لَّا يُبْصِرُونَ
Their example is that of one who kindled a fire, but when it illuminated what was around him, Allah took away their light and left them in darkness [so] they could not see.
صُمٌّۢ بُكْمٌ عُمْىٌ فَهُمْ لَا يَرْجِعُونَ
Deaf, dumb and blind - so they will not return [to the right path].