The Cow - 2:16
They have bought error in exchange for guidance. Their trade will not profit them nor will it lead them to the truth.
The most profitable trade:
The Ranks/61:10
O you who believe, shall I show you a trade that will save you from a painful torment?
يَٓا اَيُّهَا الَّذ۪ينَ اٰمَنُوا هَلْ اَدُلُّكُمْ عَلٰى تِجَارَةٍ تُنْج۪يكُمْ مِنْ عَذَابٍ اَل۪يمٍ
The Ranks/61:11
You believe in Allah and His messenger and strive in the way of Allah with your lives and your money. That is best for you, if you only knew.
تُـؤْمِنُونَ بِاللّٰهِ وَرَسُولِه۪ وَتُجَاهِدُونَ ف۪ي سَب۪يلِ اللّٰهِ بِاَمْوَالِكُمْ وَاَنْفُسِكُمْۜ ذٰلِكُمْ خَيْرٌ لَـكُمْ اِنْ كُنْتُمْ تَعْلَمُونَۙ