The only known example of a linnod, a certain type of Sindarin poetry.
This verse probably consists out of two parts with 7 syllables each with the stress pattern XxxXxXx (X = stressed syllable, x = unstressed syllable), and the following metre:
¯ ˘ ˘ | ¯ ˘ ˘ | ̆ || ¯ ˘ ˘ | ¯ ˘ ˘ | ̆
¯ = long syllable
˘ = short syllable
_̆ = short or long syllable
One thing to note about Tolkien's use of the negative prefix ú- was later explained as with the sense 'bad, uneasy, hard', adding:
úchebin will mean not 'I do not keep', but 'I cannot keep'. [PE22/160]
For a more contemporary negative prefix, see law-/ló-.