David sware moreover The matter being of great moment, and Jonathan doubting the truth of it, he confirms his word with an oath, which follows in the end of the verse. Only he interposeth a reason why Saul concealed it from Jonathan. Let not Jonathan know this, lest he be grieved What a noble and generous turn does David here give to the behaviour of Saul to Jonathan, lest he should think ill of his father, by insinuating that he had kept this a secret from him out of affection, lest it should give him pain.
Related Commentaries of 1 Samuel 20:3
1 Samuel 20:3
3 And David sware moreover, and said, Thy father certainly knoweth that I have found grace in thine eyes; and he saith, Let not Jonathan know this, lest he be grieved: but truly as the LORD liveth, and as thy soul liveth, there is but a step between me and death.