4 Bible Verses about Political Alliances, By Oaths

So Jonathan made a covenant with the house of David, saying, Let the LORD even require it at the hand of David's enemies. And Jonathan caused David to swear again, because he loved him: for he loved him as he loved his own soul.

Now therefore swear to me here by God, that thou wilt not deal falsely with me, nor with my son, nor with my son's son: but according to the kindness that I have done to thee, thou shalt do to me, and to the land in which thou hast sojourned.

And they said, We saw certainly that the LORD was with thee: and we said, Let there be now an oath betwixt us, even betwixt us and thee, and let us make a covenant with thee; That thou wilt do us no hurt, as we have not touched thee, and as we have done to thee nothing but good, and have sent thee away in peace: thou art now the blessed of the LORD. And he made them a feast, and they ate and drank.read more.
And they rose betimes in the morning, and swore one to another: and Isaac sent them away, and they departed from him in peace.

And Joshua made peace with them, and made a league with them, to let them live: and the princes of the congregation swore to them. And it came to pass at the end of three days after they had made a league with them, that they heard that they were their neighbors, and that they dwelt among them. And the children of Israel journeyed, and came to their cities on the third day. Now their cities were Gibeon, and Chephirah, and Beeroth, and Kirjath-jearim.read more.
And the children of Israel smote them not, because the princes of the congregation had sworn to them by the LORD God of Israel. And all the congregation murmured against the princes. But all the princes said to all the congregation, We have sworn to them by the LORD God of Israel: now therefore we may not touch them. This we will do to them; we will even let them live, lest wrath be upon us, because of the oath which we swore to them.