Abraham operated under the Law of Faith. He started the tithe. Jacob continued the practice. Both came before the Old Testament Law was even established.
Why did Abraham tithe? Does the Bible tell us why he gave that tenth? What was the purpose of his tithe? Was it to teach us tithing or did it have a greater purpose?
Jacob's vow to tithe; did he ever keep it? Should our giving be based upon his example? Lord, if I win the lottery, I will give my pastor 10% of all I make. Lord, you get me out of debt and keep me out of debt, and I'll give my pastor 10% of all I make.
Obviously, you really don't know much about Abraham's tithe nor Jacob's vow to tithe.
There is nothing in Abraham's tithe to Melchizedek that even remotely resembles the type of tithing that pastors in churches are promoting today. God even chose not to even record a motive as to why he gave the tithe. For all we know it was because of some crazy custom or tax that they had during that day. We have no clue and so we can only speculate or assume, and both of which are not great foundational premises on which to base "Sound" doctrine.
God refers back to Abraham's tithe several times throughout Scripture; first in Psalm 110:4 and then in Hebrews 5, 6, and 7. Every reference to the event was in regards to Jesus Christ being our High Priest after the order of Melchizedek. In other words, God's emphasis is not on the tithe but what the tithe accomplished. This event was not recorded so that God could establish a system that would benefit Him, but instead to benefit us. Man needed salvation. We know that we needed Christ to be our perfect sacrifice for our sin, but God also knew that we needed a perfect Priest to make the offering as well. Jesus could not be our high priest after the order of Aaron, He needed to be after a greater order and so God created the perfect type of order through Melchizedek and the tithe was simply the tool used to do so.
Abraham gave only one tithe because that was all that God needed in order to set up Melchizedek as a type of Christ. Abraham also gave this tithe before he had any children, therefore according to Hebrews chapter 7, all of his offspring paid this tithe as well. Now, since Abraham was not saved when he gave this tithe, all Christians as well paid this tithe also. You see, Abraham was not saved in chapter 14 during this event, it was in chapter 15, Abraham was saved and therefore all of Abraham's spiritual seed as well paid this tithe to Melchizedek. Do you understand we too paid this tithe to Melchizedek through our father Abraham?
Jacob's vow to tithe had no ramifications on the Christian, because Christians are not and never will be considered the children of Israel or the children of Jacob. That honor falls on the Jews who are still alive and well today. When Jacob vowed to tithe from the land of that God gave him, he set his children up to pay it, because Jacob could not keep the vow since he never took possession of the land that God had just promised him in his dream. Since his children were not yet born, they were still yet in his loins and therefore were obligated to pay the tithe from the inheritance.
God later gave the tithe to the Levite. It was now theirs as part of their inheritance. As long as the Jew is in the Land of Israel, they are obligated to pay the tithe to the Levite. The problem today is that, no Jew knows what tribe they actually belong to. One day that will be sorted out and the tithe will once again be re-instituted back in their land.
The Levite was the only people in the world that was given a commandment to collect a tithe from a people. Not your pastor, not your church, not one single person alive today. All of the tithe that is from the Land of Israels belongs to God and in turn belongs to the Levite. Since we are not farming any of the land of Israel, no tithe is required.
God gave us another commandment and that was to love one another. Our giving is based upon meeting others needs as they are laid upon our hearts by the Holy Spirit of God.