Truce

In situations where there are two opposing sides that are generally neutral towards each other or even allies with each other, you can call for a truce. This generally requires important information (we were sent by the merchants guild), certification from an important or recognizable organization (legal documentation) or a special item (an artifact or flag).

It could also be appropriate to call for a truce if you are delving into a dungeon and encounter another party, so long as you aren't after the same thing. You might not cooperate, but at least you won't be killing each other. If more information is revealed by talking throughout a battle (wait you're also hunting for the garbooni?), you can also reasonably call for a truce.