76 Thus it is not by any means to be made a matter of doubt that the Lord Himself spoke all these words, some of them with a literal import, and others of them with a figurative, although the evangelists may have introduced them only in part into their writings—one inserting one section, and another giving a different portion. Certain passages, at the same time, have been recorded in identical terms either by some two of them, or by some three, or even by all the four together.
And yet not even when this is the case can we take it for granted that everything has been committed to writing which was either uttered or done by Him. Moreover, if any one fancies that the Lord could not in the course of the same discourse have used some expressions with a figurative application and others with a literal, let him but examine His other addresses, and he will see how rash and inconsiderate such a notion is. For, then (to mention but a single instance which occurs meantime to my mind), when Christ gives the counsel not to let the left hand know what the right hand does, he may suppose himself under the necessity of accepting in the same figurative sense at once the almsgivings themselves referred to, and the other instructions offered on that occasion.
Source: The Harmony of the Gospels (New Advent)