Narrated Ibn al-Sa'idi: 'Umar reported me to collect the sadaqah (i.e. zakat). When I became free, he ordered to give me payment for it. I said: I have worked for the sake of Allah. He said: Take what you have been given, for I held an administrative post in the time of the Messenger of Allah (ﷺ), and he gave me payment for it.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا أَبُو الْوَلِيدِ الطَّيَالِسِيُّ، حَدَّثَنَا لَيْثٌ، عَنْ بُكَيْرِ بْنِ عَبْدِ اللَّهِ بْنِ الأَشَجِّ، عَنْ بُسْرِ بْنِ سَعِيدٍ، عَنِ ابْنِ السَّاعِدِيِّ، قَالَ اسْتَعْمَلَنِي عُمَرُ عَلَى الصَّدَقَةِ فَلَمَّا فَرَغْتُ أَمَرَ لِي بِعُمَالَةٍ فَقُلْتُ إِنَّمَا عَمِلْتُ لِلَّهِ . قَالَ خُذْ مَا أُعْطِيتَ فَإِنِّي قَدْ عَمِلْتُ عَلَى عَهْدِ رَسُولِ اللَّهِ صلى الله عليه وسلم فَعَمَّلَنِي .
sunnah.com