Summer retreat (Skt. varṣā, Wyl. dbyar gnas) a three-month, or one month and half in the Tibetan tradition, depending of the way of counting, generally beginning after the full-moon day of the eight lunar month (usually July), during which time monks are required to remain in residence in on place. The Buddha instructed monks to stay in one place during the monsoon period in order to prevent the killing of insects and worms while walking on muddy roads. It is one of the three basic rituals of the Vinaya.