All 3 Uses

lament
in
The Hobbit
(Auto-generated)

They were still standing over him, cursing their ill luck, and Bombur's clumsiness, and lamenting the loss of the boat which made it impossible for them to go back and look for the hart, when they became aware of the dim blowing of horns in the wood and the sound as of dogs baying far off.†
p. 135.4

lamenting = expressing grief or regret
why did we not remember Beorn's advice, and Gandalf's!" he lamented.†
p. 144.6

lamented = expressed grief or regret
...and down the wind came the voices of the people of Esgaroth lamenting their lost town and goods and ruined houses.
p. 229.4 *

lamenting = expressing regret for

Definitions:

(1) (lament)
to express grief or regret
(2) (meaning too rare to warrant focus)
Although lament typically refers to a feeling or simple vocal expression, it can refer to a vocal expression as complex as a sad song or poem. It can even refer to sad, but non-vocal music -- as when Tennessee Williams references background music in A Streetcar Named Desire.