This psalm is purely Messianic, and was always considered to be so. When Jesus quoted it in His conversation with the rulers, it is perfectly evident that they looked upon it in that light. [Matthew 22:43; Mark 12:36; Luke 20:42; Acts 2:34; Hebrews 1:13; 5:6]. The psalm stands alone, as not having a primary reference to an earthly King, like other Messianic Psalms, indirectly prophetic of Messiah. The picture drawn in this Psalm, with two utterances of revelation, (v. 1) and (v. 2). The first of which is expressly stated to be a declaration of the LORD (Father), and the second declared to be unchangeable, because accompanied by His oath, form the two central points of the train of thought pursued in this Psalm.
The first utterance of God assigns to the Lord of the Psalmist a place at the right hand of The Father, with the promise of the complete overthrow of His enemies.Verse 110:2 takes this as the ground of an address to this Lord (Son), in which there is promised to Him, by the help of The LORD, a triumphant extension of His kingdom out of Zion. Verse 110:3 pledges the willing loyalty of His people, which constantly rejuvenates itself, as a nation of numberless warriors, and consecrates itself to God. This is done in connection with the declaration of The LORD contained in the second divine utterance. This Ruler is a Priest forever, after an order not Levitical, but reaching back to the unhistorical past (Hebrews 7:17, 21). And verses 5~7, describe the victorious career of this Hero, who crushes His foes with the might of God.