The Tenth Commandment of the Law of God:

“Thou shalt not covet thy neighbor’s wife, thou shalt not covet thy neighbor’s house, nor his land, nor his manservant, nor his ox, nor his ass, nor anything that is thy neighbor’s.”
The tenth commandment of the Lord God forbids not only doing something bad to someone near us, but also forbids even bad desires and thoughts in connection with them. The sin against this commandment is called envy. A person who is envious, who entertains the idea of wanting something that belongs to someone else, can pass from the desire to the evil deed. But beyond this, envy in itself can defile the soul, rendering it impure before God, as it is stated in the Word of God, The thoughts of the wicked are an abomination to the Lord (Prov. 15:26, Wis. of Sol. 2:25).
One of the main tasks of true Christianity is to cleanse one’s soul of all impurity, in accordance with the admonition of the Apostle, Let us cleanse ourselves from all filthiness of the flesh and spirit, perfecting holiness in the fear of God (II Cor. 7:1).
In order to avoid sin against the tenth commandment, it is necessary to maintain a pure heart, free of any earthly attachment, free of all wicked thoughts and desires, and to be satisfied with that which one has, to thank God for it, never to desire anything that is anyone else’s, but to rejoice for others in what they have.