The tithe is the Lord's. You must clearly understand this to have a basic understanding of what it is to truly trust the Lord in the area of finances. This is exemplified by a life of obedience. God's word reveals that the tithe belongs to Him. God simply asks that we obey His commandments and trust Him to provide for all of our needs. The man who does not tithe or give, trusts more in his own ability than God's goodness and faithfulness.
“And he (Abram) gave him (Melchezedek) a tithe of all.” Genesis 14:20
“And all the tithe of the land, whether of the seed of the land or of the fruit of the tree, is the Lord’s. It is holy to the Lord.” Leviticus 27:30