Albert Barnes Commentary 1 Samuel 14:39

"For, as Jehovah liveth, who saveth Israel, though it be in Jonathan my son, he shall surely die. But there was not a man among all the people that answered him." — 1 Samuel 14:39 (ASV)

Saul’s rashness becomes more and more apparent. He now adds an additional oath, to bring down yet further guilt for “taking God’s name in vain.” The expressions in 1 Samuel 14:36 and 1 Samuel 14:40 indicate the fear in which the people stood of Saul. None dared to resist his will.