At Sāvatthī.
“Mendicants, did you hear an old jackal howling at the crack of dawn?”
“Yes, sir.”
“There might be some gratitude and thankfulness in that old jackal, but there is none in a certain person here who claims to follow the Sakyan.
So you should train like this:
‘We will be grateful and thankful.
We won’t forget even a small thing done for us.’
That’s how you should train.”
The Linked Discourses with similes are complete.