And Melchizedek king of Salem brought forth bread and wine: and he was the priest of the most high God. And he blessed him, and said, Blessed be Abram of the most high God, possessor of heaven and earth: And blessed be the most high God, which hath delivered thine enemies into thy hand. And he gave him tithes of all.
Genesis 14:18-20 KJV
The rebellious nature of man is easily seen when there is mention made of the tithe. More excuses are formulated to avoid simple loving obedience to the Word of God than you can shake a stick at.
The tithe was before the law, during the law, and after the law. Tithing is holy honor and thanksgiving to God. Get over your fear and receive the rewards.
Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the Lord of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it. And I will rebuke the devourer for your sakes, and he shall not destroy the fruits of your ground; neither shall your vine cast her fruit before the time in the field, saith the Lord of hosts. And all nations shall call you blessed: for ye shall be a delightsome land, saith the Lord of hosts. Malachi 3:10-12 KJV
(Also, read Hebrews 7)