一切經音義 25.146

25.146

如龜藏六（龜有頭尾四足名為六處若侵惱則藏入殼中眾生六根馳流外境塵賊來侵自守根門如龜藏六也）。

Like a tortoise concealing its six limbs (A tortoise has a head, tail, and four legs, which are called its six places; if harassed, it withdraws them into its shell. Sentient beings' six sense faculties run toward external objects; when the sense-thieves come to attack, they guard their own faculty-gates, just as a tortoise conceals its six limbs).