"'God sells righteousness at a very low price to those who wish to buy it: a little piece of bread, a cloak of no value, a cup of cold water, a mite.'"

Abba Epiphanius, Bishop of Cyprus 16 (PG 65, col. 168).  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 Épiphane.  The desert Christian:  sayings of the Desert Fathers:  the alphabetical collection, trans. Benedicta Ward (New York, NY:  Macmillan Publishing Co., Inc., 1975), 59.