The Prophet ﷺ said, "Whoever we appoint to a position and provide with a wage, anything he takes beyond that is stolen property."
حدثنا زيد بن أخزم أبو طالب حدثنا أبو عاصم عن عبد الوارث بن سعيد عن حسين المعلم
عن النبي ﷺ قال من استعملناه على عمل فرزقناه رزقا فما أخذ بعد ذلك فهو غلول
[Its isnad is hasan]. Ibn Khuzayma narrated it, no. 2369, from Zayd, through him. Hakim ruled it sahih according to the standard of the two Shaikhs, 1/406, and Dhahabi agreed with him.