OK, all you Buddhist scholars - here's an interesting challenge -

We are all familiar with the Buddha's "earth-touching" mudra and we all "know" that it is based upon the Buddha calling on the earth as witness when challenged by Mara. But, in re-reading some of the early Pali writings, I cannot find a single work containing that reference. Instead, what I am finding is that, when the Buddha was confronted by the full might of Mara's armies, Phra Mae Thorani ["Mother Earth"] rose up and, wringing all the earth's waters from her hair, swept away Mara's armies in the resulting flood.

The Lalitavistara "Sutra" does contain the "calling the Earth as witness" account, but this work is really considered more as equivalent to the Jataka Tales than as an actual account of the Buddha's enlightenment. It did inspire the stone carvings at Borobdur, though.

So, the challenge is to find any more mentions of the "earth as witness" story. Have fun!