Where?
Matt ch 15...
verses 25-26:
The woman came and knelt before him. “Lord, help me!” she said.
He replied, “It is not right to take the children’s bread and toss it to their dogs.”
She even agrees, referring to herself as a dog in verse 27:
“Yes, Lord,” she said, “but even the dogs eat the crumbs that fall from their masters’ table.”
The whole outcome is in verse 28:
Then Jesus answered, “Woman, you have great faith! Your request is granted.” And her daughter was healed from that very hour.
The story is also in Mark ch 7.