D&C 118 - 121

While in Far West, the Prophet inquired of the Lord regarding how much was expected of the saints in the paying of their tithes. I'm not sure what inspired the Prophet to approach the Lord on this matter, but I can only speculate that with all the persecutions and with the saints being expelled from their homes and properties in Jackson and Clay counties, times must have been financially difficult. It is the Lord's answer to the Prophets supplication that established the modern-day definition of this law.

Initially the saints were to put -

"...their surplus property... into the hands of the bishop of my church in Zion,
2 For the building of mine house, and for the laying of the foundation of Zion and for the priesthood, and for the debts of the Presidency of my Church." (Doctrine and Covenants Section 119:1 - 2)

"And this shall be the beginning of the tithing of my people." (Doctrine and Covenants Section 119:3)

Following this initial donation, the Lord instructed -

"...after that, those who have thus been tithed shall pay one–tenth of all their interest annually; and this shall be a standing law unto them forever, for my holy priesthood, saith the Lord." (Doctrine and Covenants Section 119:3 - 4)

For all-

"...who gather unto the land of Zion shall be tithed of their surplus properties, and shall observe this law..." (Doctrine and Covenants Section 119:5)

But not only those that gather in the land of Zion for -

"...this shall be an ensample unto all the stakes of Zion..." (Doctrine and Covenants Section 119:7) or in other words, all members of the Church.

Zion by definition means -

"...for this is Zion—THE PURE IN HEART..." (Doctrine and Covenants Section 97:21)

The law of tithing seems to be a "cleansing of the heart" law. A law of sanctification. A law where man chooses obedience in lieu of appetite and worldly desires. A law of faith where man must outwardly demonstrates his faith in God over the material things of this world. For the Lord said -

"...if my people observe not this law, to keep it holy, and by this law sanctify the land of Zion unto me, that my statutes and my judgments may be kept thereon, that it may be most holy, behold, verily I say unto you, it shall not be a land of Zion unto you." (Doctrine and Covenants Section 119:6)

And the Lord instructs that his tithes -

"...shall be disposed of by a council, composed of the First Presidency of my Church, and of the bishop and his council, and by my high council; and by mine own voice unto them, saith the Lord." (Doctrine and Covenants Section 120:1)