Charles Spurgeon Commentary 1 Samuel 20:28-30

"And Jonathan answered Saul, David earnestly asked leave of me to go to Beth-lehem: and he said, Let me go, I pray thee; for our family hath a sacrifice in the city; and my brother, he hath commanded me [to be there]: and now, if I have found favor in thine eyes, let me get away, I pray thee, and see my brethren. Therefore he is not come unto the king`s table. Then Saul`s anger was kindled against Jonathan, and he said unto him, Thou son of a perverse rebellious woman, do not I know that thou hast chosen the son of Jesse to thine own shame, and unto the shame of thy mother`s nakedness?" — 1 Samuel 20:28-30 (ASV)

Then Saul's anger was kindled against Jonathan, and he said to him, Thou son of the perverse rebellious woman, do not I know that thou hast chosen the son of Jesse to thine own confusion, and unto the confusion of thy mother's nakedness?

He was in such a rage that he began to abuse his own wife, the mother of his own son. In the East, if you want to sting a man most severely, insult his mother; and surely, in the West as well, if anyone has anything to say against a man's mother, it cuts her son to his heart if he is the son he ought to be.