'Assurance' in the Bible

And the work of righteousness shall be peace; and the effect of righteousness, quietness and assurance for ever.

to the end that their hearts may be encouraged, being united together in love, and unto all riches of the full assurance of understanding, to the full knowledge of the mystery of God;

For our glad tidings were not with you in word only, but also in power, and in the Holy Spirit, and in much assurance; even as ye know what we were among you for your sakes:

For we are become companions of the Christ if indeed we hold the beginning of the assurance firm to the end;

But we desire earnestly that each one of you shew the same diligence to the full assurance of hope unto the end;

let us approach with a true heart, in full assurance of faith, sprinkled as to our hearts from a wicked conscience, and washed as to our body with pure water.