"Ach Gott, vom Himmel sieh darein" ("Oh God, look down from heaven") is a Lutheran chorale of 1524, with words written by Martin Luther paraphrasing Psalm 12.

The text inspired vocal and organ music by composers such as Heinrich Schütz, who set it as part of his Becker Psalter, and Johann Sebastian Bach, who based a chorale cantata on it.

[citation needed] In the first Lutheran hymnal the melody was the same as for "Es ist das Heil uns kommen her" by Paul Speratus (Zahn No. 4430).

This melody is in Phrygian mode, preferred by Luther for texts of repentance, such as "Aus tiefer Not schrei ich zu dir".

Mozart used the melody in his opera Die Zauberflöte in act 2, Finale, scene 10, when the two "Geharnischte" (men in armour) recite it in unison on Schikaneder's words "Der, welcher wandert diese Strasse voll Beschwerden" as a cantus firmus of a Baroque-style chorale prelude.

Alfred Einstein commented in his biography Mozart / His Character, His Work:In the second act it is the final test of the lovers, the "'test of fire and water", for which Mozart called into play every musical means at his disposal and for which he ordained extreme simplicity, extreme mastery; the scene of the men in armor, which he constructed in the form of a chorale prelude, building upon a solemn fugato around the chorale Ach Gott, vom Himmel sieh darein ...[12]