Some time after Saul’s conversation with David, Jonathan also spoke to him. In terms of becoming one in spirit, the same Hebrew phrase is used in reference to Jacob and his son Benjamin (Genesis 44:30). It implies a deep friendship and commitment to the well-being of each other.1 Jonathan recognized in David a kindred spirit, a man who was concerned for God and his glory in the same way that Jonathan was.2
1 As soon as he had finished speaking to Saul, the soul of Jonathan was knit to the soul of David, and Jonathan loved him as his own soul.