Psalm 116:6King James Version (KJV)
6 The Lord preserveth the simple: I was brought low, and he helped me.
This promise is part of psalm 116, where David is explaining his love for the Lord who heard his voice and supplications. In his moment of trouble he called upon the Lord and the Lord helped him.
To me this promise of God is an assurance that when calling upon the Lord in our lowest moment he will hear us. We just have to have a childlike faith!