The Fellowship of the Ring, “Fog on the Barrow-Downs”. Tom answers the Hobbits the next day after they have sung the song above.

Old Tom Bombadil is a merry fellow,
Bright blue his jacket is, and his boots are yellow.
None has ever caught him yet, for Tom, he is the master:
His songs are stronger songs, and his feet are faster.

Provided by: NenyaGold