'Assured' in the Bible

Then I said, Ah, Lord Yahweh! behold, the prophets tell them, You shall not see the sword, neither shall you have famine; but I will give you assured peace in this place.

and being fully assured that what he had promised, he was also able to perform.

One man esteems one day as more important. Another esteems every day alike. Let each man be fully assured in his own mind.

But you remain in the things which you have learned and have been assured of, knowing from whom you have learned them.