Numbers 18:25-26 New International Version (NIV)
25 The Lord said to Moses, 26 “Speak to the Levites and say to them: ‘When you receive from the Israelites the tithe I give you as your inheritance, you must present a tenth of that tithe as the Lord’s offering.
No one was exempt from returning a portion of what was received. God expects all his followers to supply the material needs of those who devote themselves to meeting the spiritual needs of the community of faith. Ask God to direct you about what you should give and to help you give generously.