Matthew 5:39
37 Let your word be ‘Yes, yes’ or ‘No, no.’ More than this is from the evil one. 38 “You have heard that it was said, ‘An eye for an eye and a tooth for a tooth.’ 39 But I say to you, do not resist the evildoer. But whoever strikes you on the right cheek, turn the other to him as well. 40 And if someone wants to sue you and take your tunic, let him have your coat also. 41 And if anyone forces you to go one mile, go with him two.
Didache 1:4
4 Refrain from indulging in carnal and bodily desires. If someone strikes you on the right cheek, turn to them the other cheek also, and you will be perfect. If someone compels you to go one mile, go two. If someone takes your coat, offer them your shirt as well. If someone takes from you what belongs to you, do not refuse, even if you can. 5 Give to everyone who asks of you, and do not refuse, for the Father's will is that we give to all from the gifts we have received. Blessed is the one who gives according to the mandate, for they are innocent; but those who receive without need shall be questioned as to why they took and for what purpose. They shall be examined for their deeds while in prison, and they shall not be released until they pay the last farthing.
Notes and References
"... Unit 4b-d presents a text which is close to Matt. 5:39b-41. This especially obtains for Did 1:4b and Matt 5:39b, although the somewhat awkward wording of striking someone on his right cheek in 1:4b is slightly different from its stylistically better Matthean counterpart. The Didache's simple way of putting it, however, may corroborate the impression that this version has retained the more primitive text ..."
Sandt, Hubertus W., and David Flusser The Didache: Its Jewish Sources and Its Place in Early Judaism and Christianity (p. 44) Royal Van Gorcum, 2002