The prayer Ashrei ends with the verse Va'anachnu from Psalm 115. This concluding line was added at least as early as the 9th century, possibly so that we finish on the word Hallelujah, or perhaps so that there are an even number of verses (to facilitate responsive reading). In the late 19th century, David Davis, the choirmaster at New West End Synagogue set Va'anachnu to this melody from Felix Mendelssohn's oratorio, "Elijah". Since we open the ark to return the Torah immediately following this recitation of Ashrei, the original text for this melody makes for quite an apposite contrafactum: "Open the heavens and send us relief. Help, help Thy servant now, o God".