Llef (in English "A Cry") is a popular Welsh hymn, written by David Charles (1803-1880) (son of David Charles (1762–1834)). The tune was composed in 1890 by Griffith Hugh Jones ( Welsh language name Gutyn Arfon) (1849–1919) and was written in memory of his brother Dewi.
The meter is 8-8-8-8 and the key is D minor. English texts also commonly sung to the tune include "Bow Down Thine Ear, O Lord, and Hear", "Glorying in the Cross of Christ" and "The Day of Wrath".
The hymn was included in the soundtrack for the 1941 John Ford drama film How Green Was My Valley.