Albert Barnes 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)

Jonathan went into the city - From this, we can infer—as the subsequent history also indicates—that Jonathan’s filial duty and patriotism prevented a complete rupture with his father. Jonathan’s conduct in this, as in everything, was most admirable.