'Thank offerings' in the Bible

Then Hezekiah answered and said, Now you have consecrated yourselves unto the LORD, come near and bring sacrifices and thank offerings into the house of the LORD. And the congregation brought in sacrifices and thank offerings; and as many as were of a free heart burnt offerings.

And he repaired the altar of the LORD, and sacrificed on it peace offerings and thank offerings, and commanded Judah to serve the LORD God of Israel.