1 Samuel 25:16
They were a wall unto us both by night and day, all the while we were with them keeping the sheep.
Cross-reference
In 1 Samuel 25:7, David claims they didn't harm the shepherds; here Nabal's servants confirm they were a protective wall.
1 Samuel 22:2 describes the distressed men who joined David — here in 25:16 they prove faithful and protective, showing their character.
Psalm 38:20 speaks of repaying good with evil — exactly what Nabal does to David's men who protected his shepherds.
In Job 1:10, God hedged Job about — similarly, the servant describes David's men as a protective wall around them.
In Jer 15:20, God makes Jeremiah a fortified wall — here the servant says David's men were a wall of protection day and night.
Zechariah 2:5 uses 'wall of fire' for God's protection — a similar protective barrier image as the literal wall David's men provided.