Vikkhepapaṭibāhanatoti kammaṭṭhānaṃ vissajjetvā bahiddhā puthuttārammaṇe cetaso vikkhepo paṭibāhitabbo.
Ñ(VIII,65): 4. As to warding off distraction: he must ward off [temptation] to drop the meditation subject and to let his mind get distracted among the variety of external objects.
Appaṭibāhato hi yathā nāma ekapadikaṃ papātamaggaṃ paṭipannassa purisassa akkamanapadaṃ asallakkhetvā ito cito ca vilokayato padavāro virajjhati, tato sataporise papāte patitabbaṃ hoti, evameva bahiddhā vikkhepe sati kammaṭṭhānaṃ parihāyati paridhaṃsati.
Ñ: For if not, just as when a man has entered on a one-foot-wide cliff path, if he looks about here and there without watching his step, he may miss his footing and fall down the cliff, which is perhaps as high as a hundred men, so too, when there is outward distraction, the meditation subject gets neglected and deteriorates.
Tasmā vikkhepapaṭibāhanato manasikātabbaṃ.
Ñ: So he should give his attention to it warding off distraction.