I have come across a couple of web pages recently which talk about urban legends that regularly surface in sermons. Two of these, apparently, are that the 'Eye of the Needle' is a gate into Jerusalem and that Gehenna was the rubbish dump outside Jerusalem that was continually burning. While these both have a long tradition of being taught there is no evidence from early times that they are true.
The most recent web page I went to included the 'dust of the rabbi' as an urban legend. This is something that I have read in both Rob Bell (Velvet Elvis) and John Ortberg (God is Closer Than You Think). The idea is that Jewish students were encouraged to follow their rabbi so closely as he walked along that they would get coated in the dust kicked up by his feet. The value, obviously not being in the dust, but in the close proximity to the example and teaching of the rabbi.
I was surprised to see this listed as an urban legend - although I know that it has been said that Rob Bell tends to read too much from the 2nd century Judaism back into Jesus' time, I find John Ortberg to be pretty reliable. I did a bit of researching.
I discovered that Rob Bell had or has an association with Willow Creek Community Church - I didn't know that. At any rate he spoke about 'Dust' there according to their archived programme. At this stage John Ortberg was on staff there and was part of the programme with Rob Bell. I was a bit disappointed to discover that my two 'independent' sources were not independent! Not that there is anything wrong with them not being independent, or both speaking at Willow Creek - it just changes things when you are looking for the truth behind a story.
It turns out (if you read the books carefully) that they both credit Dutch teacher Ray vander Laan with the insights about the dust of the rabbi. He sounds like a fascinating teacher and I think I must get hold of one of his dvd's. (His webpage is at www.followtherabbi.com.)
I can't find out anything about Ray vander Laan's sources - so the trail that I have been following was cut off.
The only readily available source for the 'dust' idea comes from the Mishnah. A tractate called the 'Avot' (or 'Aboth') - The Sayings of the Fathers. These are the words of 1:4
Yosei ben Yoezer of Tzreida and Yosef ben Yoch
anan of Yerushalayim received from him.Yosei ben Yoezer of Tzreida says,
Make your house a meeting house for the sages;
and get sooty in the dust of their feet, and drink with thirst their words.
Given that John Ortberg uses this in the context of Mary sitting at Jesus's feet, it seems to be relevant. I think that these authors may have taken a little license in expanding the principle from the Mishnah, but I don't think it is so far out of court to call the concept an urban legend.
Wikipedia Avot Tractate chapter 1
Tom Seid - including the commentary from the Talmud
A contemproary Jewish commentary on this passage from the Mishnah