It is narrated about Hazrat Sha'bi that a goat ate flour. And another narrator says that it ate yarn, so Sha'bi declared it void and recited this verse: {إِذْ نَفَشَتْ فِیہِ غَنَمُ الْقَوْمِ }. And in the hadith of Ibn Abi Khalid, it is said that Nafsh (grazing) happens at night.