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 be a follower of the Sakyan son.

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.