Following are a number of back-translations of Romans 12:20:

• Uma: “So, follow the teaching of the Holy Book long ago that says: ‘If your (sing.) enemies are hungry, feed them. Or if they are thirsty, give them something to drink. If you (sing.) do like that, they will end up being ashamed.'” (Source: Uma Back Translation)
• Yakan: “But do as is said in the holy-book, ‘If you (happen-to-) see your enemy hungry, feed (him). If he is thirsty, cause (him) to drink. If you do this to him, he will finally be very ashamed.'” (Source: Yakan Back Translation)
• Western Bukidnon Manobo: “Let us on the advice of the written word of God which says, ‘If your enemy is hungry, feed him; if he is dry, give him something to drink. For if this what you do, he will become very much ashamed because of his harm to you.'” (Source: Western Bukidnon Manobo Back Translation)
• Kankanaey: “And you should not only do that but rather you should also follow what God caused-to-be-written which says, ‘If your (sing.) enemy is hungry, feed him; if he is thirsty, give-him-a-drink; because if you (sing.) do that, he will be extremely shamed.'” (Source: Kankanaey Back Translation)
• Tenango Otomi: “Also it is written about the word God says ‘If you see that your enemy is hungry, give him food to eat. If you see that he is thirsty, give him water to drink. If you do to your enemy according to these works, then he will become ashamed, because there will come to his heart the evil he has done to you.'” (Source: Tenango Otomi Back Translation)

For the Old Testament quote, see Proverbs 25:21 and Proverbs 25:22.