'Truly' in the Bible

“But if you refuse and rebel,You will be devoured by the sword.”Truly, the mouth of the Lord has spoken.

Now in that day the remnant of Israel, and those of the house of Jacob who have escaped, will never again rely on the one who struck them, but will truly rely on the Lord, the Holy One of Israel.

Truly, O Lord, the kings of Assyria have devastated all the countries and their lands,

Truly, You are a God who hides Himself,O God of Israel, Savior!

Calling a bird of prey from the east,The man of My purpose from a far country.Truly I have spoken; truly I will bring it to pass.I have planned it, surely I will do it.