"Then they reverted to their heads [i.e., their former state of disbelief]," meaning: disgraced, for he had refuted them; so they said, "You already knew that these do not speak."
﴿ثمَّ نكثوا على رُءُوسهم﴾ أَيْ: خَزَايَا قَدْ حَجَّهُمْ؛ فَقَالُوا: ﴿لَقَدْ عَلِمْتَ مَا هَؤُلاءِ يَنْطِقُونَ﴾.
