四分律刪補隨機羯磨 2.182

2.182

(At one time, there was a bhikṣu who came to his dwelling place for the retreat but forgot and did not bind it. The Buddha said: "If he came for the sake of the retreat, it is thereby effected as a retreat." In the Vinaya, this was for a visiting bhikṣu who originally had an appointment and came from outside to lodge; forgetting to bind it was excused, but if there were resident monks, it is not within this general allowance. If there was prior arrangement, the principle applies equally to guest and host.)