Map and key for the Eribor?

Stands in the first chapter of the Hobbit; An unexpected feast.

When Gandalf Thorin gives the card and the key.

“I didn’t bring them to me <, it was entrusted to me," said the magician

…

“… your father Thrain has gone on a twenty-first April, last Thursday a hundred years ago, and you haven’t seen him again…”

…

“Your grandfather,” said the magician slowly and darkly, “the card gave his son in custody before he turned up to the mines of Moria. After your grandfather had been killed, your father left with the map to try his luck; … but never only came near the mountain. When I found him, he was a prisoner in the tidings of the necromant!

…

I tried to save your father, but it was too late. He was no longer intellect and was wrong; he had forgotten almost everything except for the map and the key.”

…

“… Your father wanted one thing: that his son was studying this card and used the key. …