Once Buddha was walking from house to house begging for alms with his disciples. The disciples were young and inexperienced, but full of enthusiasm and reverence for their teacher. Buddha told them that as monks their duty was to be content with whatever the householders offered them, so they did as he said.
Sometimes they were fed generously, other times they received little, but they were always treated with respect, or at worst indifference. One time, however, the man who opened the door lashed out in insults. He called Buddha a useless leech, a fraud, a cheat, a despicable bastard, a whole host of other terrible things, lambasted the entire monk profession, spat on the ground, and slammed the door. Unfazed, Buddha merely turned around to leave for the next house, and, as always, the disciples followed suit.
But for the rest of the day the disciples could not get that incident out of their mind. Their minds were ablaze with rage. How dare he treat our master with such contempt! What a great insult! What arrogance! On and on and on it went, but they did not say a word to their teacher. In this way the whole day passed.
At nightfall they stopped at a spot to rest. It was a long and tiring day so one of the disciples got some water and started to wash and massage Buddha's feet. The rest sat nearby and ate their food. Buddha looked around and noticed that they were eating their food a little more violently than usual. What's wrong?, he asked.
Then it all came gushing out. That man who insulted you, they said, he is such a scoundrel, such a fiend, such a...
Once they were done, Buddha looked around and smiled. He only said: If someone gives you a cow, and you refuse to take it, to whom does it belong?