Charles Ellicott Commentary 1 Samuel 20:42

"And Jonathan said to David, Go in peace, forasmuch as we have sworn both of us in the name of Jehovah, saying, Jehovah shall be between me and thee, and between my seed and thy seed, for ever. And he arose and departed: and Jonathan went into the city." — 1 Samuel 20:42 (ASV)

Go in peace.— The abruptness of the closing words is most natural, and accords with the evident deep emotion of the speaker. David’s heart was too full to reply to his friend’s words; blinded with tears, he seems to have hurried away speechless.

“We may indeed wonder at the delicacy of feeling and the gentleness of the sentiments which these two men in those old rough times held for one another. No ancient writer has presented to us so noble an example of a heartfelt, unselfish, and thoroughly human state of feeling, and none has described friendship with such entire truth in all its relations, and with such complete and profound knowledge of the human heart.”— Phillipson, quoted by Payne Smith.