釋氏要覽 2.100

2.100

The Brief History of the Clergy says: 'Precept knives are all implements of the Dharma. According to the Vinaya, one is permitted to keep a crescent-bladed knife for the purpose of cutting cloth.' That monks today keep a knife called a 'precept [knife]' is because the Buddha did not permit the felling or cutting of any vegetation so as not to destroy the villages of spirits and ghosts. If vegetation is still subject to precepts, how much more so anything else!