Deception for righteous purposes

فَلَمَّا جَهَّزَهُم بِجَهَازِهِمْ جَعَلَ ٱلسِّقَايَةَ فِى رَحْلِ أَخِيهِ ثُمَّ أَذَّنَ مُؤَذِّنٌ أَيَّتُهَا ٱلْعِيرُ إِنَّكُمْ لَسَـٰرِقُونَ

So when he had furnished them with their supplies, he put the [gold measuring] bowl into the bag of his brother. Then an announcer called out, "O caravan, indeed you are thieves."