وَالدَّلِيلُ عَلَى أَنَّ أَكْرَ الْمَرْءِ نَفْسَهُ فِي الْعَمَلِ طَلْقٌ مُبَاحٌ، إِذْ هُوَ مِنِ ابْتِغَاءِ فَضْلِ اللَّهِ لِأَخْذِهِ الْأُجْرَةَ عَلَى ذَلِكَ
The evidence for this is that taking payment for permissible work is absolutely correct because this is earning wages for labor on Allah’s bounty (trade), and taking this wage is permissible.