'Troth' in the Bible

“Open the gates, that the righteous nation may enter,The one that remains faithful and trustworthy.

“Then I passed by you [again] and looked on you; behold, you were maturing and at the time for love, and I spread My skirt over you and covered your nakedness. Yes, I swore [an oath] to you and entered into a covenant with you,” says the Lord God, “and you became Mine.”