'Burden' in the Bible

And Naaman said, If not, yet, I pray thee, let there be given to thy servant two mules burden of earth; for thy servant will henceforth offer neither burnt-offering nor sacrifice unto other gods, but unto Jehovah.

So Hazael went to meet him, and took a present with him, even of every good thing of Damascus, forty camels burden, and came and stood before him, and said, Thy son Benhadad king of Syria hath sent me to thee, saying, Shall I recover of this sickness?

Then said Jehu to Bidkar his captain, Take up, and cast him in the portion of the field of Naboth the Jezreelite; for remember how that, when I and thou rode together after Ahab his father, Jehovah laid this burden upon him: