When King Suddhodana came to know that the Buddha was teaching in Rajagaha he sent nine messengers, one after the other, inviting him to come to Kapilavatthu. All the messengers became monks. They listened to the Buddha's teachings and found them so appealing that they forgot to convey the king's message.
The king had made arrangements for the Buddha to stay in a park called Nigrodha. But when the Buddha did not arrive, the king sent Kaludayi, a childhood playmate of Buddha's, to invite him back to Kapilavatthu.
When the people of Kapilavatthu discovered that the Buddha had come to their city they flocked to see him. Prince Siddhartha's own relatives came as well and said, "He is our younger brother, our nephew, our grandson."
Then the Buddha realised that some people, even then, did not understand that he was already enlightened but felt they were his elders. He showed them a miracle called the "Twin miracle". Even the king, seeing this miracle, worshipped him.
The next day the Buddha took his begging bowl and went from door to door begging for food. The king, seeing this, was very annoyed. "Why do you disgrace me, my son? Why do you ruin me like this? Why don't you take food in the palace? Is it proper for you to beg for food in this very city where you used to travel in golden sedan chairs? Why do you put me to shame, my dear son?"
"I am not putting you to shame, O Great King. This is our custom," replied the Buddha calmly.
"How can this be? Nobody in our family has ever begged like this. How can you say 'it is our custom'?" the confused king asked.
"Oh Great King, this is not the custom of the Royal family, but of the Buddhas. All the former Buddhas have lived by receiving food this way."
However, when the king begged the Buddha to take food in the palace the Buddha kindly did so.