My MSc thesis is about a subject that my adviser isn't completely familiar with. In my work, I found some new result. He said it is better to show the results to one of his friend that has expertise and is more familiar with this subject.
I suggested to first publish a pre-print in arXive, before showing result to others, but he objected I should just publish a completed work. However, I don't know if I can trust his friend or not.
What can I do?