James Ramsey Murray (1841-1905) was an American music teacher, songwriter and editor of songbooks for Sunday schools. He printed this tune in 1887 under the title Luther's Cradle Hymn, and again in 1892 in his Little Sacred Songs for Little Singers, with a note saying that Martin Luther had written the carol for his children. The story is a legend: the words are anonymous and American, and no German original has ever been found.
In the United States the carol is sung to Murray's melody, known in hymnals as Mueller. In Britain the same words are usually sung to Cradle Song, a different tune written in 1895 by the American hymn composer William J. Kirkpatrick. If the melody on this page is not the one you know, you probably learned the carol to Kirkpatrick's tune.
This transcription: James R. Murray, "Luther's Cradle Hymn" (tune Mueller), as printed in his Little Sacred Songs for Little Singers (Cincinnati: John Church Co., 1892), p. 39, archive.org littlesacredsong00murr, page n42: the melody in F major as printed; left hand by GOONS Studio.
Transcribed by GOONS Studio from the original work, which is in the public domain.
On guitar: Away in a Manger guitar chords and lyrics, with a guitar that strums along.
For kids: Away in a Manger by colors, on a rainbow piano that lights the next key and waits.