The Gospel of Pseudo-Matthew 5Chapter 4.

After these things, her nine months being fulfilled, Anna brought forth a daughter, and called her Mary. And having weaned her in her third year, Joachim, and Anna his wife, went together to the temple of the Lord to offer sacrifices to God, and placed the infant, Mary by name, in the community of virgins, in which the virgins remained day and night praising God. And when she was put down before the doors of the temple, she went up the fifteen steps so swiftly, that she did not look back at all; nor did she, as children are wont to do, seek for her parents. Whereupon her parents, each of them anxiously seeking for the child, were both alike astonished, until they found her in the temple, and the priests of the temple themselves wondered.