Rúmil, the aged door-ward, says to Eriol:
'(...) This morn I felt as Ómar the Vala who knows all tongues, as I hearkened to the blending of the voices of the birds, comprehending each, recognising each well-loved tune (...)' BOLT1, 47
Last of all came Ómar who is called Amillo, youngest of the great Valar, and he sang songs as he came.
In The Coming of the Elves (BOLT1, 122) it is described how each of the three elven tribes were particularly loved by some of the great Valar. We learn how Ulmo favours the Solosimpi (the later Teleri) and Aulë the Noldoli (Noldor). But also that:
Manwë loved more the Teleri, and from him and Ómar did they learn deeper the craft of song and poesy than all the elves beside.
N.B.: The Teleri are the elvenfolk who in the Silmarillion became known as the Vanyar.
See further this article on Salmar, which contains much information on Amillo/Ómar for you to graspJ.