Gabriel Faure composed his Requiem in D minor, Op. 48 between 1887 and 1890. This choral orchestral setting of the Roman Catholic Mass for the Dead is the best known of his large works. The most famous movement is the soprano aria Pie Jesu. Camille Saint-Saens said of it, "just as Mozart's is the only Ave verum Corpus, this is the only Pie Jesu."
Here is a setting for cello quartet.
The PDF file contains the score and parts.