Pia et humilis ad deum oratio, latine (CPG 4088)*
This text appears in M.F. Toal, Sunday Sermons of the Great Fathers, 4 vols. (London, 1955-1963). It comes from vol. 4, p. 406. See here for more information on this valuable collection.
* See Assemani Gr. 3:578.
Saint Ephrem the Syrian 