Saint Patrick went to Tara to cure Lugaid son of Laeghaire son of Niall of the Nine Hostages of a “trouble”. Lugaid took a large piece of bread and swallowed it and it stuck in his throat. Patrick gave him milk to drink, but it made the bread swell up, and it choked Lugaid to death.
Patrick prayed “crosfigell” (kneeling with his arms spread in the form of a cross) for three days and three nights. Saint Michael the Archangel appeared and restored Lugaid to life. Patrick commanded that everyone should set aside a tenth portion of food for the King of the Clouds and a morsel for Michael.
(from the early 15th-century Book of Lismore 22.86 a39, included in my forthcoming Meath Folk Tales)