The "Dead March" is an instrumental section from the Oratorio "Saul" with music by Handel and a libretto by Charles Jennens. It is a stately and respectful funeral march marked "Symphony" in the score to indicate its instrumental nature. The march comes toward the end of the Oratorio for the death of Saul and his son. As a hymn-like funeral march this music is often heard at Funerals and Remembrance Services.
The instrumental score has been laid out in full though the parts for similar instruments have been combined for the sake of economy, since the piece is quite short. Here is the Full Score and the parts for 2 Flutes (with optional oboes), 2 Trombones, Bass Trombone, Timpani, Violins 1 and 2, Violas, Cellos and Basses and expanded continuo part for Organ. Though perhaps surprising to modern audiences, trombones were often used in religious music in the past. There is an illustrative video of the sheet music below where you can also see the score and audio versions. Alternatively the parts, midi and mp3 files can be downloaded from the left-hand menu.
Here is a video of Handel's Dead March from Saul:
The image below is the first page of the sheet music, and here you can download the full sheet music for Handel's Dead March from Saul in PDF format.