"ashes," is found three times, twice in association with sackcloth, Matthew 11:21; Luke 10:13 , as tokens of grief (cp. Esther 4:1,3; Isaiah 58:5; 61:3; Jeremiah 6:26; Jonah 3:6 ); of the ashes resulting from animal sacrifices, Hebrews 9:13; in the OT, metaphorically, of one who describes himself as dust and "ashes," Genesis 18:27 , etc.
"to turn to ashes," is found in 2 Peter 2:6 , with reference to the destruction of Sodom and Gomorrah.
Notes: (1) Tephra, frequently used of the "ashes" of a funeral pile, is not found in the NT. (2) The Hebrew verb, rendered "accept" in Psalm 20:3 , "accept thy burnt sacrifice," signifies "to turn to ashes" (i.e., by sending fire from heaven). See also Exodus 27:3; Numbers 4:13 , "shall take away the ashes."