'Knows' in the Bible

David said, “While the child was still alive, I fasted and wept; for I thought, ‘Who knows, the Lord may be gracious to me and the child may live.’

Joab bowed his face toward the ground and lay himself down and blessed the king. Then Joab said, “Today your servant knows that I have found favor in your sight, my lord, O king, in that the king has done the request of his servant.”

And even the one who is brave, whose heart is like the heart of a lion, will completely lose heart and melt away; for all Israel knows that your father is a mighty man, and that those who are with him are brave men.

For your servant knows that I have sinned; therefore, behold, I have come today, the first of all the house of Joseph to come down to meet my lord the king.”