When you speak faith

“From the fruit of a man's mouth his stomach is satisfied; he is satisfied by the yield of his lips.” (Prov. 18:20 ESV)

 The power of what you say 

“Death and life are in the power of the tongue, and those who love it will eat its fruits.”  (Prov. 18:21 ESV)

 Speak with faith without doubt in your heart

“Truly, I say to you, whoever says to this mountain, ‘Be taken up and thrown into the sea,’ and does not doubt in his heart, but believes that what he says will come to pass, it will be done for him.” (Mark 11:23 ESV)

 Confess with your mouth that Jesus is Lord

“Because, if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved.” (Rev. 10:9 ESV)

For God has said 

"I have put My words in your mouth and have covered you with the shadow of My hand, to establish the heavens, to found the earth, and to say to Zion, 'You are My people.'" (Isa. 51:16 NASB)

Therefore…

“Let the words of my mouth, and the meditation of my heart, be acceptable in thy sight, O LORD, my strength, and my redeemer.” (Psalm 19:14 KJV)