John Gill's  Exposition of the Bible 

1 Chronicles 12:1

Now these are they that came to David to Ziklag, while he yet kept himself close because of Saul the son of Kish: and they were among the mighty men, helpers of the war.

Now these are they that came to David to Ziklag,.... Given him by Achish to live in, when he fled from Saul, 1 Samuel 27:6

while he yet kept himself close, because of Saul the son of Kish; when he was an exile from his own country, and obliged to live retired in a foreign one, because of Saul's persecution of him, and seeking to take away his life:

and they were among the mighty men, helpers of the war; not against Saul, with whom David had none, but with the Amalekites, and others, 1 Samuel 27:8.