Let all mortal flesh keep silence (Greek: Σιγησάτω πᾶσα σάρξ βροτεία), also known as Let all mortal flesh keep silent, is an ancient chant of Eucharistic devotion based on words from Habakkuk 2:20, "Let all the earth keep silence before him" (Hebrew: הַ֥ס מִפָּנָ֖יו כָּל־הָאָֽרֶץ has mippanaw kol ha-arets). The original was composed in Greek as a Cherubic Hymn for the Offertory of the Divine Liturgy of St James; it probably antedates the rest of the liturgy and goes back at least to AD 275, with local churches adopting arrangements in Syriac. [Source: Wikipedia 
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