It happened as they came, when David returned from the slaughter of the Philistine, that the women came out of all the cities of Israel, singing and dancing, to meet king Saul, with tambourines, with joy, and with instruments of music.
He set up a dowry regarding the Philistines. David went out and gave him double dowry. So Saul then of course was sort of shocked and surprised. He figured David would get wiped out in going out against the Philistines.