4 Bible Verses about Political Alliances, By Oaths

So Jonathan {made a covenant} with the house of David, [saying,] "May Yahweh {call the enemies of David to account}." And Jonathan again made David swear an oath, because he loved him; for with the love of his soul he loved him.

So now, swear to me here by God [that] you will not deal with me falsely, or with my descendants, or my posterity. According to the kindness that I have done to you, you shall [pledge] to do with me and with the land where you have dwelled as an alien."

And they said, "We see clearly that Yahweh has been with you, so we thought let there be an oath between us--between us and you--and let us {make} a covenant with you that you may not do us harm just as we have not touched you, but have only done good to you and sent you away in peace. You [are] now blessed by Yahweh." So he made a meal for them, and they ate and drank.read more.
And they arose early in the morning and each one swore to the other, and Isaac sent them away. And they left him in peace.

And Joshua made peace with them, and {he made a covenant with them} to allow them to live happily, and the leaders of the congregation swore [an oath] to them. And it happened that at the end of three days, after they made a covenant with them, they heard that {they were their neighbors} and living among them. And the {Israelites} set out and went to their cities on the third day (their cities [were] Gibeon, Kephirah, Beeroth, and Kiriath Jearim).read more.
But the {Israelites} did not attack them, because the leaders of the congregation had sworn to them by Yahweh the God of Israel. And all the congregation murmured {against their leaders}. But all the leaders of the congregation said, "We have sworn to them by Yahweh the God of Israel, and so we cannot touch them. This we will do to them: [we will] let them live so that wrath will not be on us because of the oath we swore to them."