Dharmaguptaka-vinaya 15.12

15.12

不犯者，取水及楊枝，若不受酥油脂灌鼻與唾俱出，餘者不犯。若乞食比丘鳥銜食墮鉢中，若風吹墮鉢中，欲除去此食乃至一指爪可除去，餘者無犯。

As for anāpatti: taking water and tooth-sticks; if unreceived ghee, oil, or fat is used as nasal drops and comes out together with saliva, the remainder is anāpatti. If a bird carries food and drops it into an alms-begging bhikṣu's bowl, or if the wind blows food and it drops into his bowl, and he wants to remove this food, removing up to a fingernail's breadth, the remainder is anāpatti.