Ibn al-Sa'idi (may Allah be pleased with him) said: Umar bin al-Khattab (may Allah be pleased with him) appointed me to collect the charity. When I had finished my work, he ordered a wage for me, and I said: I worked only for Allah. Umar (may Allah be pleased with him) said: Take what you are given, for I worked in the time of the Messenger of Allah (peace and blessings be upon him), and he (peace and blessings be upon him) gave me a wage for it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 13014