Moses was a member of the tribe of Levi. As a member, he received tithes from the nation of Israel. The Levites were instructed to deliver their tithes to Aaron, the High Priest Numbers 18:26, 28 “speak unto the Levites, and say unto them, When ye take of the children of Israel the tithes which I have given you from them for your inheritance, then ye shall offer up an heave offering of it for the Lord, even a tenth part of the tithe… Thus ye also shall offer an heave offering unto the Lord of all your tithes, which ye receive of the children of Israel; and ye shall give thereof the Lord’s heave offering to Aaron the priest.” 

Additional Resource: Christian Questions Podcast Episode #1040: “Do Tithes and Offerings Belong in Christianity?” Understanding tithing and establishing Christian giving
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