“This is the declaration of the Lord to my Lord: “Sit at My right hand until I make Your enemies Your footstool.” The Lord will extend Your mighty scepter from Zion. Rule over Your surrounding enemies. The Lord has sworn an oath and will not take it back: “Forever, You are a priest like Melchizedek.” Psalms 110:1‭-‬2‭, ‬4

David, the King of Israel and the author of this Psalm, knew a thing or two about Jesus! He seems to write this Psalm to Jesus, the Messiah. According to Hebrew history, David lived from 1040 to 970bc and reigned from 1010 to 970bc, a full 967 years before Jesus was even born and 935 years before Jesus died on the cross for yours, mine and David’s sins, then rose from the dead and assended back to heaven to sit on His throne at His Heavenly Father’s right hand as King (Revelation 3:21)! I believe that David didn’t just know the Messiah was coming-HE KNEW THE MESSIAH!

Possibly this unique understanding of the coming Messiah was aquired by David because he had studied the part of the Old Testament that had already been written (roughly 1/4). I don’t think so because when he tried to bring the Ark of the Covenant back to Jerusalem with him in II Samuel 6, an incendent happened that caused him to park the cart the Ark was riding on and return to Scrpture to study proper Ark moving protocol that any student of the Torah, the first 5 books of the Bible would know!
Maybe he, as king had more access to the best scholars and teachers of his time. I don’t think so because David spent most of his younger years either running from Saul or as King, warring against the Philistines.

I believe David knew and knew about the Messiah because he understood grace and forgiveness, all out of his own sloppy life’s story!

From this passage, we see that David knew that Messiah was reigning right next to God, the Father’s throne, that He would ultimately defeat His enemy, that He did and would rule over the earth and its most powerful Kingdoms and that He was our Great High Priest after the Preistly order of Melchizedek, not Aaron’s, in other words according to God’s order of GRACE & RELATIONSHIP-not under the OT Law (Hebrews 4, 5 & 6:10 and Genesis 14).
Bottom line-there have been many through out history who have sought to please God by serving and obeying Him by doing good works in order to try to please Him. There have also been a few people through out history who understood that their personal sin and inability to stop sin separated them from God and cried out to Him for help, finding their hope and help in the fact that Messaih would come and defeat sin for them and that they could access God THRU HIM! THIS WAS DAVID! THIS IS ANYONE WHO actually has a love-based relationship with God through grace, BASED ON HIM and what HE’S DONE, or in David’s case, would do, not what we can do to EARN SALVATION! This is me! Is this you? Think about it!