«لَا تَحْسَبَنَّ أَنِّي نَأَيْتُكَ عَنْ مَلَالٍ أَوْ أَشَرِ»
Do not imagine that I went away because of boredom or arrogant high spirits.
Naʾaytu means to go away; malāl is weariness and ashar overexuberance or insolent pride. Lā taḥsabanna combines prohibition and emphatic nūn, making the denial forceful.
Yet the denial does not undo the act. Abū Zayd is explaining his motives while leaving his generous host with the consequences of his departure.