21 Those Hebrews who had previously been with the Philistines and had gone up with them to their camp went over to the Israelites who were with Saul and Jonathan.

Read 1 Samuel 14:21 Using Other Translations

Moreover the Hebrews that were with the Philistines before that time, which went up with them into the camp from the country round about, even they also turned to be with the Israelites that were with Saul and Jonathan.
Now the Hebrews who had been with the Philistines before that time and who had gone up with them into the camp, even they also turned to be with the Israelites who were with Saul and Jonathan.
Even the Hebrews who had previously gone over to the Philistine army revolted and joined in with Saul, Jonathan, and the rest of the Israelites.