'Swear' in the Bible

Go in to king David, and tell him, 'Didn't you, my lord, king, swear to your handmaid, saying, Assuredly Solomon your son shall reign after me, and he shall sit on my throne? Why then does Adonijah reign?'

It was told Solomon, saying, "Behold, Adonijah fears king Solomon; for, behold, he has laid hold on the horns of the altar, saying, 'Let king Solomon swear to me first that he will not kill his servant with the sword.'"

"If a man sins against his neighbor, and an oath is laid on him to cause him to swear, and he comes and swear before your altar in this house;