Albert Barnes Commentary 1 Samuel 14:6

"And Jonathan said to the young man that bare his armor, Come, and let us go over unto the garrison of these uncircumcised: it may be that Jehovah will work for us; for there is no restraint to Jehovah to save by many or by few." — 1 Samuel 14:6 (ASV)

It is remarkable that the epithet “uncircumcised,” used as a term of reproach, is confined almost exclusively to the Philistines (compare 1 Samuel 17:26, 1 Samuel 17:36; Judges 14:3; Judges 15:18; and others). This is probably an indication of the long oppression of the Israelites by the Philistines and of their frequent wars.