'Swear' in the Bible

Go at once to King David and say to him, ‘Did you not, my lord, O king, swear to your maidservant, saying, “Solomon your son shall certainly be king after me, and he shall sit on my throne”? Why then has Adonijah become king?’

Now Solomon was told, “Behold, Adonijah is afraid of King Solomon, and behold, he has grasped the horns of the altar [seeking God’s protection], saying, ‘King Solomon must swear to me today that he will not kill his servant with the sword.’”

So the king sent word and called for Shimei and said to him, “Did I not make you swear by the Lord and solemnly warn you, saying, ‘Know for certain that on the day you leave [Jerusalem] and go anywhere, you shall surely die’? And you said to me, ‘The word (ruling) I have heard is good.’