September 13 is the feast of Saint Neman or Naemhan distinguished in the Irish calendars by the patronymic Mac Ua Duibh. This may serve to differentiate him from Saint Neman of Cill Bia whose feast is commemorated on September 1. The 17th-century hagiologist, Father John Colgan, believed today's saint Neman to be the same individual as one mentioned in the Life of Saint Fechin of Fore. Canon O'Hanlon, however, is able only to bring us details of the feast of Saint Neman from the various Irish calendars:
St. Neman or Naemhan Mac Ua Duibh. [Probably in the Seventh Century]
We find entered in the Martyrology of Tallagh, the feast of Neman Mac h. Duibh, at the 13th of September. Marianus O'Gorman has a commemoration of this holy servant of God, at this same date, with the designation of his being prudent, while a commentator calls Noeman the great-grandson of Dub. According to Colgan, this holy man accompanied St. Fechin, Abbot of Fore, when the latter went to obtain the liberation of one Aid or Aedus from Blaithmaic and Diermit II., joint Sovereigns of Ireland. Hence his period must be assigned probably to the Seventh Century. We have recorded in the Martyrology of Donegal, the name Naemhan Mac Ua Duibh, as having a festival, at the 13th of September. In the Table appended to this latter record, we meet the Latin word sanctanus introduced, after the entry of his name.