四分律比丘含注戒本 2.617

2.617

(If one walks reaching the roads running here and there between villages, and walks reaching one road, one commits an offence. In an uninhabited open wilderness with no demarcated boundaries, if one walks together for ten li, one commits an offence. If one walks together halfway between villages, or less than ten li, or within a village, or if there is preparatory activity or making an appointment but one does not go, all are duṣkṛtas. Bhikṣuṇīs commit the same offence. As for the non-offences: if one follows along for safety in reaching somewhere, or if there are dangers to life, to brahmacarya, or due to force of power, none of these is an offence.)