Lobgesang (Hymn of Praise), Op. 52 MWV A 18, is "A Symphony-Cantata on Words of the Holy Bible, for Soloists, Chorus and Orchestra" by Felix Mendelssohn. After the composer's death it was also published as his Symphony No. 2 in B-flat major, a naming and numbering that is not Mendelssohn's.
It requires two sopranos and a tenor as soloists, along with a chorus and orchestra. It lasts almost twice as long as any of Mendelssohn's other four symphonies.