We understand that you're concerned about a friend who is about to engage in a physical altercation. We are very much against violence for any reason. First, let's pray for this situation. Then we will address some scriptures.
Dear Lord, we come to You in the great name of Jesus Christ, asking for Your intervention. Our Father, we beg You, send Your Holy Spirit to stop this fight from happening and bring peace to this situation. Keep both sides of this conflict safe from violence. Lord will you touch each person's heart involved and aid them to seek understanding, peace and forgiveness rather than violence. In the name of Jesus Christ, we agree and pray for a resolution and understanding between both parties. We thank You and praise You for Jesus Christ being the Prince of Peace. It is only in the name of Jesus we pray. Amen.
Now, let's consider what the Bible says about conflict resolution and peace. Jesus said, Blessed are the peacemakers, for they shall be called children of God Matthew 5:9 WEB.
As believers in Christ Jesus, peace should be sought, not violence or fighting, and must be pursued with other believers. It is very clear as it is stated, If it is possible, as much as it is up to you, be at peace with all men Romans 12:18 WEB. As it states in Romans 12:14, Bless those who persecute you; bless, and don't curse Romans 12:8 and love your enemies and pray for those that persecute you Matthew 5:44. The Bible says, Follow peace with all men, and sanctification Hebrews 12:14. The words fight and fighting in the Bible related to Christians is only concerning spiritual issues. In the New Testament, which concerns Christians, there is no area that allows or promotes fighting.
Since you mentioned the peace of Christ, we assume that your friend is professing to be a believer in Jesus Christ. This must be the basis for our actions as believers. The situation should not be escalated but rather be defused through meditation and prayer. If this is in a school setting then the situation needs to be reported to a teacher or administrator. If this is a work setting, report it to a manager or supervisor. This is the route to take.
Finally, let's remember that our battle is not against flesh and blood, but against the spiritual forces of wickedness in high places Ephesians 6:12. Prayer is our most powerful weapon in this battle. Thank you for turning to Jesus so the prince of peace can intervene.