1) 1 Corinthians 16 discusses the collection for the saints in Jerusalem that Paul had instructed the churches in Galatia to take up, instructing the Corinthians to set aside funds each week so there would be enough when he arrived.
2) 1 Corinthians 9 uses examples from the Old Testament and law of Moses to argue that those who minister spiritual things have a right to material support from those being ministered to, just as soldiers, farmers, shepherds, and priests received support.
3) The document discusses the various types of offerings in the Old Testament like burnt, sin, trespass, and peace offerings and explains that the purpose of these offerings was atonement, fellowship with God, worship, and obligation