Who is Mukhayriq "The best of jews"?

I've found one article on this subject on islamicity . This article states many things, that I could list one by one on here. However, it would be easier for all reading this in the future, if someone just gives us a description with islamic sources on who this man was in relation to Prophet Muhammad (PBUH). Note: I found no mention of this Jewish Rabbi at all on stack-exchange.