The Prophet (ﷺ) as saying: When we appoint someone to an administrative post and provide him with an allowance, anything he takes beyond that is unfaithful dealing.
Sunan Abi Dawud Book 20, Hadith 16
← Previous Hadith who was a Companion, reported that his mother Zainab daughter of Humain went to the Messenger of Allah (ﷺ) and said: Messenger of Allah, receive the oath of allegiance from him. The Messenger of Allah (ﷺ) said: He is Minor. He then wiped his head.

Sunan Abi Dawud Book 20, Hadith 15 Next Hadith → '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.

Sunan Abi Dawud Book 20, Hadith 17