God will give you wisdom and the right words to say

“For I will give you words and wisdom that none of your adversaries will be able to resist or contradict.” (Luke 21:15 NIV)

Do not worry, the Holy Spirit will teach you

“When you are brought before synagogues, rulers and authorities, do not worry about how you will defend yourselves or what you will say, for the Holy Spirit will teach you at that time what you should say." (Luke 12:11-12 NIV)

God will be with your mouth

“Now then go, and I, even I, will be with your mouth, and teach you what you are to say." (Ex. 4:12 NASB)

For now and forever

"As for Me, this is My covenant with them," says the LORD: "My Spirit which is upon you, and My words which I have put in your mouth shall not depart from your mouth, nor from the mouth of your offspring, nor from the mouth of your offspring's offspring," says the LORD, "from now and forever." (Isa. 59:21 NASB)