וַיֵּצְא֖וּ שָׂרֵ֣י פְלִשְׁתִּ֑ים וַיְהִ֣י ׀ מִדֵּ֣י צֵאתָ֗ם שָׂכַ֤ל דָּוִד֙ מִכֹּל֙ עַבְדֵ֣י שָׁא֔וּל וַיִּיקַ֥ר שְׁמ֖וֹ מְאֹֽד׃ (ס)
Then the princes of the Philistines went forth; and it came to pass, as often as they went forth, that David prospered more than all the servants of Saul; so that his name was much set by.
Rashi on I Samuel
The Philistines officers would venture out. To come in troops to plunder [the Bnei] Yisroel.