Our Saviour establishes His authority (Luke 20)

And He said to them, “How can they say that the Christ is the Son of David? Now David himself said in the Book of Psalms:
‘The Lord said to my Lord,
“Sit at My right hand,
Till I make Your enemies Your footstool.” ’
Therefore David calls Him ‘Lord’; how is He then his Son?”

Beware of the Scribes
Then, in the hearing of all the people, He said to His disciples, “Beware of the scribes, who desire to go around in long robes, love greetings in the marketplaces, the best seats in the synagogues, and the best places at feasts, who devour widows’ houses, and for a pretense make long prayers. These will receive greater condemnation.”

This chapter starts with our Lord being questioned by the religious leaders of the time. 

It continues with the same leaders trying to trap our Lord in the questions they answer.

Our Lord answers by first quoting Psalm 118 and finishes with verses above exposing their duplicity and ignorance whilst at the same time establishing His authority.