The stone which the builders refused is become the head stone of the corner.
What this means is the head stone of the corner is the most valued stone of the palace, and is polished to show its beauty. But the builders refuse it for the walls of the palace because it doesn't have the shape that they desire. The stones that the builders use for the walls are usually a similar cube shape like a brick. Just with different sizes and proportions. But the corner stone has a different shape that stands out and would not fit in with the wall stones.
When a Man or Woman Live by the ways of Jah and speak of those ways to others, babylon tries to keep them away from their wall stones, because they cause the wall stones to organize differently, and cause them to not fit the pattern that babylon desires.
But this stone that babylon refuses becomes the head stone of the corner, gathering the wall stones together in Inity, and displaying the glory of Jah Creation.
Haile Selassie I