1 Chronicles 12:19

Some men from Manasseh defected from the Israelite army and joined David when he set out with the Philistines to fight against Saul. But as it turned out, the Philistine rulers refused to let David and his men go with them. After much discussion, they sent them back, for they said, “It will cost us our heads if David switches loyalties to Saul and turns against us.”