Ibn Saadi reported,

Umar bin Khattab appointed me over the collection of zakat. When I finished the task and handed it over to him, he ordered that I be given a wage for my work.I said, "I worked only for the sake of Allah, and my reward is with Allah."He replied, "Take what you are given. I once worked during the time of the Messenger of Allah ﷺ, and he employed me. I said the same thing you have just said, and the Messenger of Allah told me, 'When you are given something without having asked for it, then eat from it and give in charity.'"

Azami 12478

Sahih

عن ابن الساعدي المالكي قال

استعملني عمر بن الخطاب على الصدقة فلما فرغت منها، وأديتها إليه، أمر لي بعمالة، فقلت: إنما عملت لله وأجري على الله. فقال: خذ ما أعطيت، فإني عملت على عهد رسول الله ﷺ، فعملني، فقلت مثل قولك، فقال لي رسول الله: إذا أعطيت شيئا من غير أن تسأل، فكل وتصدق.

الأعظمي 12478صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Tafsir of the great Quran
Chapter
Virtues of Surah Baqarah
Section
His saying, "Indeed, charities are for the poor and the needy and those employed to collect them and those whose hearts are to be reconciled and for freeing slaves and for those in debt and in the cause of Allah and for the traveler, an obligation from Allah. And Allah is Aleem, Wise"
Numbering
Jami al-Kamil 12478 (2nd edition)
Azami 12478