1 Samuel 28:4
And the Philistines gathered themselves together, and came and pitched in Shunem: and Saul gathered all Israel together, and they pitched in Gilboa.
Cross-reference
1 Samuel 28:15 reveals Saul's distress over the Philistine threat, the very reason he sought the medium.
1 Samuel 31:1 recounts the battle on Mount Gilboa that directly follows from the Philistine encampment at Shunem.
1 Samuel 29:1 continues the Philistine military campaign, gathering at Aphek, while the main verse has them at Shunem.
2 Samuel 1:6 gives an account of Saul's death on Mount Gilboa, the same mountain where Israel camped in the main verse.
2 Samuel 1:21 is David's lament cursing Mount Gilboa, the site of Israel's camp and Saul's defeat.
2 Samuel 21:12 mentions the Philistines slaying Saul on Gilboa, the same location as Israel's camp in the main verse.
1 Chronicles 10:1 records the same battle at Gilboa, giving the outcome: Israel fled and fell slain there.