This Melchizedek was king of Salem and priest of God Most High. He met Abraham returning from the defeat of the kings and blessed him, and Abraham gave him a tenth of everything... (Hebrews 7:1-2, NIV)
Abraham acknowledged that God had protected them, provided for them, and increased them. And he honored Him by giving the tithe to God's high priest, Melchizedek. He didn't do it to keep a rule or to be justified in His eyes, but to honor Him.
In this series, you will learn that honoring God by tithing gives Him access--opening a window into your life--so that He can bless you and protect you.