At one time the Buddha was staying near Kimibilā on the bank of the Ganges River. Seeing a large tree trunk being carried along by the current, he addressed the mendicants: “Mendicants, do you see that large tree trunk being carried along by the current of the Ganges River?” “Yes, sir,” they replied. … When this was said, Venerable Kimbila said to the Buddha: “But sir, what’s the near shore and what’s the far shore? What’s sinking in the middle? What’s getting stranded on high ground? What’s getting taken by humans or non-humans? What’s getting caught up in a whirlpool? And what’s rotting away?” … “And what, Kimbila, is rotting away? It’s when a mendicant has committed the kind of corrupt offense for which no rehabilitation is possible. This is called ‘rotting away’.”

Linked Discourses 35.243 19. The Simile of the Vipers The Explanation on the Festering

At one time the Buddha was staying in the land of the Sakyans, near Kapilavatthu in the Banyan Tree Monastery. Now at that time a new town hall had recently been constructed for the Sakyans of Kapilavatthu. It had not yet been occupied by an ascetic or brahmin or any human at all. Then the Sakyans of Kapilavatthu went up to the Buddha, bowed, sat down to one side, and said to him, “Sir, a new town hall has recently been constructed for the Sakyans of Kapilavatthu. It has not yet been occupied by an ascetic or brahmin or any human at all. May the Buddha be the first to use it, and only then will the Sakyans of Kapilavatthu use it. That would be for the lasting welfare and happiness of the Sakyans of Kapilavatthu.” The Buddha consented with silence.