I used to write (the account of) the expenditure incurred on orphans who were under the guardianship of so-and-so. They cheated him by one thousand dirhams and he paid these (this amount) to them. I then got double the property which they deserved. I said (to the man: Take one thousand (dirhams) which they have taken from you (by cheating). He said: No, my father has told me that he heard the Messenger of Allah ﷺ say: Pay the deposit to him who deposited it with you, and do not betray him who betrays you. (Using translation from Abū Dāʾūd 3534)   

كُنْتُ أَكْتُبُ لِفُلَانٍ نَفَقَةَ أَيْتَامٍ كَانَ وَلِيَّهُمْ فَغَالَطُوهُ بِأَلْفِ دِرْهَمٍ فَأَدَّاهَا إِلَيْهِمْ فَأَدْرَكْتُ لَهُمْ أَمْوَالَهُمْ مِثْلَهَا قَالَ قُلْتُ اقْبِضِ الْأَلْفَ الَّذِي ذَهَبُوا بِهِ مِنْكَ قَالَ لَا حَدَّثَنِي أَبِي أَنَّهُ سَمِعَ رَسُولَ اللهِ ﷺ يَقُولُ أَدِّ إِلَى مَنِ ائْتَمَنَكَ وَلَا تَخُنْ مَنْ خَانَكَ