Zelah was a place in the territory of the Tribe of Benjamin, ancient Judea, known as the burial place of King Saul, his father Kish and his son Jonathan. Saul and Jonathan died during the Battle of Gilboa.
Source
Wordsworth Encyclopedia of World Religions. Ware, Herts: Wordsworth (entered under Zelach: quoting Joshua 18: 21 and 2 Samuel 21: 14)