'Assuredly' in the Bible

Joshua said, “By this you shall know that the living God is among you, and that He will assuredly dispossess from before you the Canaanite, the Hittite, the Hivite, the Perizzite, the Girgashite, the Amorite, and the Jebusite.

And Moses swore on that day, saying, The land whereon thy feet have trodden shall assuredly be thine inheritance, and thy children's for ever! for thou hast wholly followed Jehovah my God.