In Psalm 80, Israel is described as the vine that Yahweh brought out of Egypt. The vine grows and extends branches, and then in judgment she is broken down. The psalmist laments the judgment and prays that God would remember the vineyard which He has planted, and the “son” which He had made strong (80:15). The vine has been burned and cut down, but the psalmist prays that God’s right hand would be upon the “man of your right hand,” upon the “son of Adam” which He has strengthened for Himself.
This “son” title for Israel goes back to the commissioning of Moses at the burning bush where Yahweh calls Israel His “firstborn son.” (Ex. 4:22)