Когда наступила ночь, Монган лежал на подушках в королевском доме, а жена сидела, в печали, справа от него. Вошел филид и потребовал уплаты долга. Но в это же самое время на южной стороне крепости появился помошник Монгана, о котором говорил он своей жене. (с)

It is probable that a prohibition existed on telling heroic tales during daytime, considering the proverb according to which "whistling at night or fiannaiocht by day" was considered unlucky. THe recital of the tales was almost without exception restricted to men. (...) There is belived to be some power in the fiannaiocht, which is apparent in an oral version
of a folktale about the mischief wrought by the devil , recorded from Galway in 1931. According to this folk-tale. the devil can not enter a second house because Fenian tales were recited there.

(c) Gerd Pettersson
Finn and the the Fian. Reflections of ancient celtic myth and institutions in early and medieval Ireland.
Göteborg 1999