One often encounters statements quoted from Rabbinical personalities or written in Seforim that they should have no apparent way of knowing. Thousands of examples could likely be given if one were to compile such a list, but one that I remember clearly having caused me to ask this question was hearing in the name of Rabbi Meir of Rottenberg that one who dies to sanctify Hashem's Name doesn't feel pain. Who told him so, and why he, not anyone else? We don't have prophets, and when looking at some of these statements, they are far more than inspired guidance or the like - they are concise detailed knowledge about things that humans generally have no knowledge aside from through direct prophecy. The only conceivable answer I can think of is that it comes via tradition (i.e., it was passed down from teacher to student until reaching that particular Rabbi who made a it more public).
Does anyone have a better explanation for this phenomenon?