﴿ حَقِيقٌ عَلَىٰٓ أَن لَّآ أَقُولَ عَلَى ٱللَّهِ إِلَّا ٱلْحَقَّ ۚ قَدْ جِئْتُكُم بِبَيِّنَةٍۢ مِّن رَّبِّكُمْ فَأَرْسِلْ مَعِىَ بَنِىٓ إِسْرَٰٓءِيلَ ﴾

“so constituted that I cannot say anything about God but the truth. I have now come unto you with a clear evidence from your Sustainer: let, then, the children of Israel go with me!"”

In the light of these clear signs he must believe him and let the children of Isra'il go with him free of his illegitimate surveillance.