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."
Matthew Henry's Commentary on 1 Chronicles 12:19
Commentary on 1 Chronicles 12:1-22
(Read 1 Chronicles 12:1-22)
Here is an account of those who appeared and acted as David's friends, while he was persecuted. No difficulties or dangers should keep the sinner from coming to the Savior, nor drive the believer from the path of duty. Those who break through, and overcome in these attempts, will find abundant recompence. From the words of Amasai we may learn how to testify our affection and allegiance to the Lord Jesus; his we must be throughly; on his side we must be forward to appear and act. If we are under the influence of the Spirit, we shall desire to have our lot among them, and to declare ourselves on their side; if in faith and love we embrace the cause of Christ, he will receive, employ, and advance us.