Romans 12:17
15 Rejoice with those who rejoice, weep with those who weep. 16 Live in harmony with one another; do not be haughty but associate with the lowly. Do not be conceited. 17 Do not repay anyone evil for evil; consider what is good before all people. 18 If possible, so far as it depends on you, live peaceably with all people.
1 Peter 3:9
8 Finally, all of you be harmonious, sympathetic, affectionate, compassionate, and humble. 9 Do not return evil for evil or insult for insult, but instead bless others because you were called to inherit a blessing. 10 For the one who wants to love life and see good days must keep his tongue from evil and his lips from uttering deceit.
Notes and References
"... If we have become skeptical about the existence of such a fixed ethical code behind Romans 9:14-21 as Talbert suggests, we must now press on either to confirm or to contradict this skepticism by our own limited cross-sectional method of investigation. We will do this indirectly by continuing our quest for the traditional form of the command behind 1 Thessalonians 5:15; Romans 12:17; and 1 Peter 3:9. We observed earlier that the similarities between Romans 12:17 and 1 Peter 3:9 point not to literary dependence but to a common tradition behind both verses. In treating 1 Thessalonians 5:15 we tried to establish that the form which this common tradition received in 1 Thessalonians 5:15 is not its traditional form, but rather the traditional form must be sought in the wording of Romans 12:17 and 1 Peter 3:9. On the basis, therefore, of the elements common to both Romans 12:17 and 1 Peter 3:9 we may conclude that the original form of the tradition contained the phrase along with the imperative participle and a negating particle ..."
Piper, John "Love Your Enemies": Jesus' Love Command in the Synoptic Gospels and in the Early Christian Paraenesis: A History of the Tradition and Interpretation of its Uses (pp. 15-16) Cambridge University Press, 1979