Psalm 103:20:

Bless the LORD, ye his angels, that excel in strength, that do his commandments, hearkening unto the voice of his word.

Notes on Psalm 103:20:

Angels obey God when He speaks, but they also hearken to the voice of His Word when they hear it from another source – your mouth!  That’s one reason why it’s so important to speak the Word out of your mouth – angels will go out and work for you when you do it!

See also:

Say What
God’s Word Is Seed
Your Heavenly Father and Your Healing
Speaking to Mountains, Trees and Diseases
The Confession UNTO Faith and the Confession OF Faith
Objection: If Proverbs 18:21 Meant What Faith Preachers Say It Does, Old Testament People Could Have Gone Around Speaking Health to the Sick and Death to Cancer and Other Diseases Before Jesus Came
Objection: Faith Must Be IN GOD (Mark 11:22), So It Is Not Something You Can Use Yourself to Change Things