«فَأَحْجَمْتُ عَنِ الْقَوْلِ إِحْجَامَ الْمُرْتَابِ وَطَوَيْتُ ذِكْرَهُ كَطَيِّ السِّجِلِّ لِلْكِتَابِ»
I held back like a hesitant man and folded away his mention as a scroll is rolled up.
Aḥjama means to draw back; ṭawaytu dhikrahu transforms concealment into the image of rolling up written pages.
The narrator is not declaring Abū Zayd beyond suspicion. He is protecting the judge’s generosity from being withdrawn on learning of the elder’s notoriety.