Why this Question (Psalm 110) from Jesus Stumped the Pharisees

Jesus stumped the Pharisees with the following question in Luke 20:41-44: Then Jesus said to them, “Why is it said that the Messiah is the son of David? David himself declares in the Book of Psalms (110): “‘The Lord said to my Lord: “Sit at my right hand until I make your enemies a footstool for your feet.”’ …