As is well known, Belatane, or the first day of May (old style), was one of the sacred days of the ancient Highlanders. In my grandfather’s youth it was the custom for the young men and maidens of Lawers to climb to the summit of Ben Lawers on that day to see the sun rise, and it was a race between the young men which of them would first reach and drink out of a spring called ‘Fuaran Bhain-tighearna Labhair’ – the Lady of Lawers’s Well.
Fragments of Breadalbane Folk-Lore, by James MacDiarmid, in Transactions of the Gaelic Society of Inverness, Volume 28 (1912-14), here.