Bible Commentary
1 Samuel 20
Jonathan's Loyalty to David and Saul's Reaction
David tries desperately to make peace with Saul. The Scriptures show that David carried himself with wisdom and the proper decorum (18:5, 30). Each month, on the occasion of the new moon, Saul held a feast at his court—apparently an important meeting to establish the agenda for the month. All the leading men were expected to be present. There had to be a very important reason to be excused.
In chapter 20 we see David leaving Samuel and going back to Saul's capital, but David fears coming into the king's presence. David's best friend, Jonathan, can't believe his father Saul intends any harm to David. But David knows better. He tells Jonathan to cover for his absence with what sounds like a reasonable excuse, explaining that Saul's reaction will reveal his intent.
King Saul sees through the explanation Jonathan gives him to excuse David. Saul becomes extremely angry at Jonathan, reviling him and disparaging his mother (verse 30)—a form of cursing that is sadly in common usage even today. Saul rages at Jonathan that he'll never be king as long as David lives (verse 31). When Jonathan attempts to reason with his father, asking what David has done to deserve death (verse 32), Saul explodes into fury and even tries to kill Jonathan—finally convincing Jonathan that there is no hope for David to reconcile with Saul (verse 33).
Jonathan carries out the predetermined method for alerting David of the threat on his life. The two meet for an emotional goodbye. Again they pledge their love and loyalty, and that of their families in perpetuity (verses 41-42).
As a note of interest, verse 26 gives internal validation of the fact that Old Testament laws were in general use at this time. (There are some who try to argue that such laws were invented much later, in the period of Ezra after the Jewish captivity in Babylon.)