Vayeira, Worshipping the Dust on Their Feet

Rashi 18:4

ורחצו רגליכם. כַּסָּבוּר שֶׁהֵם עַרְבִיִּים שֶׁמִּשְׁתַּחֲוִים לַאֲבַק רַגְלֵיהֶם וִהִקְפִּיד שֶׁלֹא לְהַכְנִיס עֲ"זָ לְבֵיתוֹ;

This morning, someone asked me what that means. Simple enough; why would anyone worship the dust on their feet? Not stam the Earth, davka the dust on their feet.

I'm told that some say they didn't worship just dust, but it was dust from their Beis Avodah Zarah. That's fine, but that is not what Rashi says, and it is not what the Gemara in BM says, or Rashi in Kiddushin that brings it as well. Instead of saying it's not shver according to X or Y, let's focus on explaining what it means according to the Gemara and Rashi.

I suggested that it was a form of ancestor worship. 

The concept is not uncommon. The Brittanica says that "Ancestor worship, prevalent in preliterate societies, is obeisance to the spirits of the dead."  I believe that it persists even today in spiritually primitive countries, such as China, and certainly in obdurately uncivilized countries such as Haiti and Togo.  

As applies to dust, of course we have Breishis 3:19,  עפר אתה ואל עפר תשוב. 

See also Shabbos 113b, that eating the dirt of Bavel is like eating one's ancestors. 

אמר ר' אמי כל האוכל מעפרה של בבל כאילו אוכל מבשר אבותיו 

Rashi

מבשר אבותיו. שמתו שם בגולה

And Hamlet act five:

“Imperious Caesar, dead and turned to clay,

Might stop a hole to keep the wind away.

Oh, that that earth, which kept the world in awe,

Should patch a wall t'expel the winter’s flaw!”

Perhaps the people of Avraham Avinu's time time worshipped their ancestors, and saw the dust that clung to their feet as the dust of their ancestors magically adhering to them.

If I were to attempt relevance, I would suggest that when we go to kivrei tzadikim, we should not ask the niftarim to give us what we need.  This is both Avoda Zara and doreish el hameisim, and, as such, is best avoided.  At most, (see Minchas Elazar 1:68, but see Igros OC 5:143:6) we might ask them to intercede with tefilla to the Ribono shel Olam on our behalf. So pay your respects, and remember that all the tefillos at that makom kadosh are to the Ribono shel Olam, instead of being משתחוה לאבק רגליך.