Munjapae 文字沛 문자패

This japanese kotowaza seems to be related to 諸葛孔明 (Koumei Shokatsu?) and his horse that he had to kill after disobeying orders.

Someone mentioned here some puns like "泣いて馬謖起きる" among other interesting 誤字ネタ.

But I still can’t figure out what that 「泣いて馬蜀を斬る」 (naite bashoku o kiru) really means nor when it is used.

Update: 孔明 (三国時代蜀の軍師) was from 蜀 (Shu) kingdom (蜀國, or Shu-Han 蜀漢, ch: 蜀汉 shŭ hàn) fighting the 魏 (Wei) kingdom (Shu seems to have failed eventually). Have to refer to 三國演義 (sān guó yăn yì) for more details about those I guess.
Another quote (名言) which seems related to 孔明: 「無欲でなかったら志を持ち続けることはできない。」