لَا تَخَلْنَا عَلَى غَرَّاتِكَ إِنَّا قَبْلُ مَا قَدْ وَشَى بِنَا الْأَعْدَاءُ
Meaning: Do not presume that your misrepresentation finds us unaware; enemies have spread tales against us before.
Lā takhalnā is a prohibition meaning “do not suppose us.” Gharrātika evokes naivety or a state of being unsuspecting. Washā binā means to carry malicious reports against us.
The speaker answers the accusation by stressing that his people have faced hostile rumours before.