Sampasadaniyasutta 2.5

2.5

So tassa nagarassa samantā anupariyāyapathaṃ anukkamamāno na passeyya pākārasandhiṃ vā pākāravivaraṃ vā antamaso biḷāranikkhamanamattampi.

As he walks around the patrol path, he doesn’t see a hole or cleft in the wall, not even one big enough for a cat to slip out.