After reading some questions posted on here I found my self reviewing Hilkhoth Tefilah, mainly the halakha of the amidah. While reading i noticed something that I have read countless times yet never popped out at me. After one prays the amidah we are instructed to preform hishtahhawayah (full body prostration) while saying tehhinoth (private supplications). In this part the halakha states that ones face must be flat on the ground and only turned to the side if one “is as righteous as Joshua”:
“ וְאֵין אָדָם חָשׁוּב רַשָּׁאי לִפֹּל עַל פָּנָיו, אֵלָא אִם כֵּן הוּא יוֹדֵעַ בְּעַצְמוֹ שְׁהוּא צַדִּיק כִּיהוֹשׁוּעַ; אֲבָל מַטֶּה הוּא פָּנָיו מְעַט, וְאֵינוּ כּוֹבֵשׁ אוֹתוֹ בַּקַּרְקָע." M"T Hilkoth Tefilah 5:14
“An important person is not permitted to fall on his face unless he is certain that he is as righteous as Yehoshua. Rather, he should tilt his face slightly, but not press it to the ground.” M"T Hilkoth Tefilah 5:14
So what exactly does this mean? Why Yehoshua Ben-Nun and why is his righteousness used for this particular halakha as a bench mark? Is there something in our mesora that links these two concepts?
EDIT: It was brought to my attention that most contributing members to Mi Yodeya hold by the S”A (of various editions) and most likely do not perform our more ancient practices of tefilah. So here are some pictures to help clarify my question.
Face flat on the ground (as the majority of yehudhim are supposed to do)
Face off to the side ( I couldn’t find an exact picture of this, since no one does this now a days, but you can see how the mans head is tilted in compared to the boys. Just imagine his body fully stretched out)
** They are on ceramic tiles NOT stone **