Buraida reported the Prophet (ﷺ) as saying, “When we appoint someone to an administrative post and provide him with an allowance, anything he takes beyond that is unfaithful dealing." Abu Dawud transmitted it.

عَن بُرَيْدَةَ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «مَنِ اسْتَعْمَلْنَاهُ عَلَى عَمَلٍ فَرَزَقْنَاهُ رِزْقًا فَمَا أَخَذَ بَعْدَ ذَلِكَ فَهُوَ غُلُولٌ» . رَوَاهُ أَبُو دَاوُد