6 Now we make offering to Him, not as though He stood in need of it, but rendering thanks for His gift, and thus sanctifying what has been created. For even as God does not need our possessions, so do we need to offer something to God; as Solomon says: “He that has pity upon the poor, lends unto the Lord.” For God, who stands in need of nothing, takes our good works to Himself for this purpose, that He may grant us a recompense of His own good things, as our Lord says: “Come, you blessed of My Father, receive the kingdom prepared for you.
For I was an hungered, and you gave Me to eat: I was thirsty, and you gave Me drink: I was a stranger, and you took Me in: naked, and you clothed Me; sick, and you visited Me; in prison, and you came to Me.” As, therefore, He does not stand in need of these [services], yet does desire that we should render them for our own benefit, lest we be unfruitful; so did the Word give to the people that very precept as to the making of oblations, although He stood in no need of them, that they might learn to serve God: thus is it, therefore, also His will that we, too, should offer a gift at the altar, frequently and without intermission.
The altar, then, is in heaven (for towards that place are our prayers and oblations directed); the temple likewise [is there], as John says in the Apocalypse, “And the temple of God was opened:” the tabernacle also: “For, behold,” He says, “the tabernacle of God, in which He will dwell with men.”
Source: Adversus haereses (New Advent)