"One of the Fathers related of Abba Sisoes of Calamon that, wishing to overcome sleep one day, he hung himself over the precipice of Petra. An angel came to take him down and ordered him not to do that again and not to transmit such teaching to others."
Abba Sisoes 33 (PG 65, col. 403/404). This one doesn't appear in the Collection systématique (SC 387, 474, and 498), or, at least, not in the Concordance (SC 498, pp. 217 ff.) under Sisoès. The desert Christian: sayings of the Desert Fathers: the alphabetical collection, trans. Benedicta Ward (New York, NY: Macmillan Publishing Co., Inc., 1975), 219.