Why should not Luke feel free to take precisely that part of a Marcan phrase which Matthew has taken—if he wanted it?
Of the peculiarly Marcan words, some prove nothing in this connection.
See the reckoning made without inclusion of Marcan Q on pp. 162, 218.
In each instance Matthew has inserted the quotation into a Marcan narrative.
No single motive, especially no one so-called “tendency” of either writer explains all his modifications of his Marcan source.
Matthew here conflates his Q material with his Marcan material.
Matthew and Luke copy the Marcan version with unusual fidelity thru about forty words.
Luke may have omitted the Marcan narrative because of this parallel of it in his own Gospel.
The addition by Matthew and Luke of the words ( ) is held by some to indicate their use of a Marcan text different from ours.
He similarly omits the Marcan account of the call of the fishermen, substituting the story of the miraculous draught.