I have enjoyed many of your responses over the past few months. However, I would respectfully disagree that the above is a solution for the apparent trouble with this passage. Frankly, this is one of the milder difficulties Jesus presents. Tearing one's eye out seems monumentally more severe.
Notice, hermeneutically the story line commencing with the Torah (Pentateuch) has not developed to include Gentiles at the point of "According to Matthew". If Paul is correct that the Law is not yet "done away with" (Heb.) and we are not grafted in until the blood is shed (Eph. 2), then Jesus is in Matt. simply teaching more of the Law to the Jews.
After all, Matt. 5:48 puts the cherry on the sundae. And, the Law is ultimately found to be impossible to fulfill (Acts 15). Thus, we are here reading someone else's mail, not tenets for "Christian Living". This hermeneutical error has long plagued the RCC which focuses heavily on "obeying" the words of Jesus...only to fail miserably at every imaginable level.
And, for someone to repeat the so-called Lord's Prayer, while ignoring the final phrase, does incredible injustice to the demands Jesus was actually presenting. Talk about not taking Him seriously! But, the evangelical community has failed to distinguish the Gospel of Jesus Christ as grace, alone (Rom. 3, Eph. 2) and instead followed in the footprints of Rome.
Rush points out absurdity by emphasizing it.