In Genesis 30:20, 34:12, Exodus 22:17, and 1 Samuel 18:25, this signifies a token of mutual consent. (Arcana Coelestia 4456)

If you think about sitting, it seems fair to say that where you're sitting is more important than that you're sitting. Sitting in a movie theater, sitting in a classroom, sitting in the driver's seat of a car, sitting in the defendant's seat at a trial, sitting at the family dinner table -- those are very, very different things. But even so, the fact that you're sitting in those places is important -- it means you are part of what's going on, you're staying in place. This is similar to "sitting" in the Bible. Sitting on a throne indicates judgment; sitting in a tent door indicates holiness. The context is crucial. But in all cases "sitting" indicates a sense of permanence, belonging, and full participation in the spiritual state illustrated through the context.