Bible Verse about Pure Heart:
“Create in me a pure heart, O God, and renew a steadfast spirit within me.”
When you face failure and lose hope, ask God to give you a new heart which is filled with courage and confidence. When you really repent for you sins and realize that you have sinned against God, ask God to bless you with a pure heart which is filled with stable and firm spirit.
Nothing can shake that spirit, when the God Almighty has given it to you. But always remember not to corrupt that pure heart and spirit with evil and sin again. Make a promise to yourself, that you will keep it pure as God gave it to you.