Your mouth is a powerful tool in you receiving your salvation. Romans 10:10 says, "For with the heart man believeth unto righteousness, and with the mouth confession is made unto salvation." That word confession means to acknowledge or say the same thing as. So, let's break this scripture down, notice it says, with the mouth(your mouth) confession(saying the same thing as God) is made unto salvation(healing, deliverance, preservation, made whole). That word salvation means so much more than only being born again. That scripture is saying when you speak God's word out of a believing heart your words will bring your salvation. It's not you just speaking anything, but God's word. Understand, God has something for you to say that will bring you deliverance. Proverbs 12:6 says, "The mouth of the upright will deliver them." Understand, God has something for you to say in that sickness. Proverbs 12:18 says, "But the tongue of the wise is health." That word health is translated remedy, medicine, cure. God's word will keep you that's why Proverbs 14:3 says, "The lips of the wise will preserve them." Notice when it says lips, mouth, or tongue it is referring to your words.
The Bible is full of instances of people who knew how to speak their deliverance like David going up against Goliath when he said, "This day will the Lord deliver you into my hands." And soon after he spoke those words Goliath's head was in his hands. And the 3 Hebrew boys that was facing being thrown into the fiery furnace and they spoke that the Lord would deliver them from the hands of the king. And after they were thrown into the furnace they came out without one hair burned and without even the smell of smoke. How about the woman with the issue of blood, she spoke, "If only I may touch his clothes, I shall be made whole." Their words were key to them receiving their salvation and your words are key to you receiving your salvation. So, when you are going through a tough time find out what God has said about your situation and put your faith in that and let your words come into agreement with his word. God has already promised that his word would not return to him without accomplishing what he pleases. His words return to him from your lips. Follow the instructions God gave Joshua, "This book of the law shall not depart out of your mouth, but thou shalt meditate therein day and night." And the same thing He promised Joshua is for you, "And you shall make your way prosperous."