The Quran

قُل هَل أُنَبِّئُكُم بِشَرٍّ مِن ذٰلِكَ مَثوبَةً عِندَ اللَّهِ ۚ مَن لَعَنَهُ اللَّهُ وَغَضِبَ عَلَيهِ وَجَعَلَ مِنهُمُ القِرَدَةَ وَالخَنازيرَ وَعَبَدَ الطّاغوتَ ۚ أُولٰئِكَ شَرٌّ مَكانًا وَأَضَلُّ عَن سَواءِ السَّبيلِ

Muhammad Asad

Say: "Shall I tell you who, in the sight of God, deserves a yet worse retribution than these? They whom God has rejected and whom He has condemned, and whom He has turned into apes and swine because they worshipped the powers of evil:¹ these are yet worse in station, and farther astray from the right path [than the mockers].²

Contrary to many of the commentators who take this reference to "apes and swine" in a literal sense, the famous tabi'i Mujahid explains it as a metaphorical description (mathal) of the moral degradation which such sinners undergo: they become wildly unpredictable like apes, and as abandoned to the pursuit of lusts as swine (Manor VI, 448). This interpretation has also been quoted by Tabari in his commentary on 2:65. - As regards the expression "powers of evil" (at-,taghut), see surah 2, note 250.
As is evident from the following verses, the sinners who are even worse than the mockers are the hypocrites, and particularly those among them who claim to be followers of the Bible: for the obvious reason that, having been enlightened through revelation, they have no excuse for their behaviour. Although in verse 64 the Jews are specifically mentioned, the reference to the Gospel in verse 66 makes it clear that the Christians, too, cannot be exempted from this blame.