[311] Bhikkhus, in whomever mindfulness directed to the body (kāyagatā sati) has been developed and cultivated, Māra gains no opening in him, Māra gains no foothold (ārammaṇa) in him. Bhikkhus, suppose a man were to throw a light ball of string against a door-panel made entirely of heartwood. What do you think, bhikkhus—would that man's light ball of string find an opening in that door-panel made entirely of heartwood?
"No indeed, venerable sir."
"Even so, bhikkhus, in whomever mindfulness directed to the body has been developed and cultivated, Māra gains no opening in him, Māra gains no foothold in him."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.