John Gill Commentary Luke 20:44

"David therefore calleth him Lord, and how is he his son?" — Luke 20:44 (ASV)

David therefore called him Lord Or, "my Lord", as the Syriac and Ethiopic versions read; or, "his Lord", as the Arabic version. This is the inference from the words before cited (Psalms 110:1) , upon which the following question is asked, how is he then his son ? how can these things be reconciled? in what sense can he be both his Lord and son? (See Gill on Matthew 22:45).