"Those are the ones who have purchased error in exchange for guidance." Meaning: they chose error over guidance, according to the exegesis of al-Hasan. "And their transaction has brought no profit, and they were not guided."
Muhammad said: Meaning, they did not profit in their transaction.
﴿أُولَئِكَ الَّذِينَ اشْتَرَوُا الضَّلالَةَ بِالْهُدَى﴾ يَعْنِي: اخْتَارُوا الضَّلَالَة عَلَى الْهدى؛ فِي تَفْسِير الحَسَن ﴿فَمَا رَبِحَتْ تِجَارَتهمْ وَمَا كَانُوا مهتدين﴾.
قَالَ مُحَمَّد: يَعْنِي: فَمَا ربحوا فِي تِجَارَتهمْ.