We stand with you in prayer for your friend who is experiencing these spiritual attacks and discouragement. The Bible reminds us that "we don't wrestle against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, and against spiritual forces of evil in the heavenly places" (Ephesians 6:12, WEB).
Firstly, let's address the negative words spoken over your friend. The Bible is clear that "death and life are in the power of the tongue" (Proverbs 18:21, WEB). Negative words can bring discouragement and fear, but we must remember that God has not given us a spirit of fear, "but of power, love, and self-control" (2 Timothy 1:7, WEB).
Let us pray:
"Dear Heavenly Father, we come before you in the name of Jesus Christ to lift up our friend who is feeling overwhelmed by negative words and forces he can't control. Lord, you are the God of all comfort, and we ask that you comfort him now. Rebuke the spirits of discouragement, fear, and poverty that have been spoken over him. Remind him of your truth, that you have a plan to prosper him and not to harm him, plans to give him hope and a future (Jeremiah 29:11, WEB). Equip him with your armor, so he can stand firm against the schemes of the devil (Ephesians 6:11, WEB). In Jesus' name, we pray. Amen."
Encourage your friend to replace the negative words with God's promises. He should memorize and declare scriptures over his life, such as "I can do all things through Christ, who strengthens me" (Philippians 4:13, WEB) and "For God didn't give us a spirit of fear, but of power, love, and self-control" (2 Timothy 1:7, WEB).
Lastly, ensure that your friend has accepted Jesus Christ as his Lord and Savior. It is only through Jesus that we have access to God and can resist the devil (James 4:7, WEB). If your friend has not yet accepted Jesus, share the Gospel with him and encourage him to confess with his mouth the Lord Jesus, and believe in his heart that God has raised him from the dead, for with the heart one believes unto righteousness, and with the mouth confession is made unto salvation (Romans 10:9-10, WEB).