"The LORD be between me and thee, and between my seed and thy seed forever." (1 Samuel 20:42)
In "Word Focus" for this week's lesson, Dr. Glenn McClure writes:

At this point in our lesson, David knew two important facts: First, God’s purpose was unfolding as the life of His “anointed” was being preserved, for Samuel had chosen him in the name of God. Second, he and Jonathan had made a sacred oath. Loyalty to each other was not by the force of this oath, but the oath was only proof of their loyalty. David had respect for God’s timing and still saw Jonathan as a “prince,” thus, he “bowed himself three times” to Jonathan. Further proof of his loyalty is seen in the latter part of our lesson (2 Sam. 9:1-7). Yet Jonathan’s loyalty is to be admired, for he recognized God’s hand upon David. He had the power to take David’s life, but his love for David and the Lord superseded any desire for an earthly throne. Both of these men maintained a loyalty to God’s will. As a result they were able to be loyal to each other in the working out of His will.

Source: Biblical Family Values, Adult Teacher's Insights, page 70.