I am a mathematician. What's the go-to reference for a proper math-based introduction to martingale theory and arbitrage pricing?
The books I am being referred to deal mostly either with the discrete case, or, if its continuous, then it does not contain all the proofs and there's a lot of hand-waving (for example, Bjork's Arbitrage theory in Continuous time, which does not even contain proper proofs of, say, the fundamental theorem of finance or the all-important Ito formula).