'Assuredly' in the Bible

It happened in those days, that the Philistines gathered their armies together for warfare, to fight with Israel. Achish said to David, "Know assuredly that you shall go out with me in the army, you and your men."

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?'

She said to him, "My lord, you swore by Yahweh your God to your handmaid, 'Assuredly Solomon your son shall reign after me, and he shall sit on my throne.'

most certainly as I swore to you by Yahweh, the God of Israel, saying, 'Assuredly Solomon your son shall reign after me, and he shall sit on my throne in my place;' most certainly so will I do this day."

Yes, I will rejoice over them to do them good, and I will plant them in this land assuredly with my whole heart and with my whole soul.