12 Therefore, whatever you want others to do for you, do also the same for them, for this is the Law and the Prophets.
Matthew 7:12
I will owe nothing to anyone except to love them, for he who loves his neighbor has fulfilled the law. For the commandments, “You shall not commit adultery,” “You shall not murder,” “You shall not steal,” “You shall not covet,” and if there is any other commandment, it is summed up in this saying: “You shall love your neighbor as yourself.” Love does no harm to a neighbor; therefore love is the fulfillment of the law.
Romans 13:8–10
The importance of “doing unto others what you would have them do unto you” found in Obadiah (verse 15):
For the day of the Lord is near, against all the nations. As you have done, it will be done to you; what you deserve will return on your own head.
Obadiah 15
Jesus confirms how we will be judged:
7:1 “Do not judge, so that you won’t be judged. 2 For you will be judged by the same standard with which you judge others, and you will be measured by the same measure you use.
Matthew 7:1-2
3 Why do you look at the splinter in your brother’s eye but don’t notice the beam of wood in your own eye? 4 Or how can you say to your brother, ‘Let me take the splinter out of your eye,’ and look, there’s a beam of wood in your own eye? 5 Hypocrite! First take the beam of wood out of your eye, and then you will see clearly to take the splinter out of your brother’s eye. 6 Don’t give what is holy to dogs or toss your pearls before pigs, or they will trample them under their feet, turn, and tear you to pieces.
Matthew 7:3-6