'Full Assurance' in the Bible

that their hearts may be comforted, they being firmly united in love in order to gain all the riches of the full assurance of understanding, that they may acknowledge the mystery of God, even the Father, and of Christ,

For our gospel came not to you in word only, but also in power, and in the Holy Spirit, and in full assurance, as you know what sort of persons we were among you for your sakes.

let us draw near with a true heart, in full assurance of faith, having; our hearts sprinkled from an evil conscience, and our bodies washed with pure water;