Jesus is talking to a group of people about what they as individuals should and should not do. The "you" is plural in "you have heard" and "I say to you." The understood "you" is singular in "Do not commit adultery," but in some languages it may need to be plural. (See: rc://en/ta/man/translate/figs-you)
Jesus agrees with God and his word, but he does not agree with the way the religious leaders had applied God's word. The "I" is emphatic. This indicates that what Jesus says is equally important to the original commands from God. Try to translate this phrase in a way that shows that emphasis. See how you translated this in [Matthew 5:22](./21.md).
This metaphor indicates that a man who lusts after a woman is as guilty of adultery as a man who actually commits the act of adultery. (See: [[rc://en/ta/man/translate/figs-metaphor]])