Sutta Reference

In the book by Ayya Khema, the following section can be found in a chapter discussing the benefits of solitude: >"... Once the Buddha went to a village where nobody had any faith in him. Nobody in the village paid any attention to him, and he received no alms food at all. He went to the outskirts and sat down on a bit of straw and meditated. Another ascetic, who saw that the Buddha had not received any food, commiserated with him: “You must be feeling very bad, not having anything to eat. I’m very sorry. You don’t even have a nice place to sleep, just straw.” >The Buddha replied, “Feeders on joy we are. Inner joy can feed us for many days ...”. Unfortunately there are not any references to the story in the book. Would anyone happen to know the sutta reference? Thank you for your time.