Ambrose of Milan — as excerpted in the Catena Aurea on Matthew 5:10

“(in Luc. vi. 23.) Otherwise; the first kingdom of heaven was promised to the Saints, in deliverance from the body; the second, that after the resurrection they should be with Christ. For after your resurrection you shall begin to possess the earth delivered from death, and in that possession shall find comfort. Pleasure follows comfort, and Divine mercy pleasure. But on whom God has mercy, him He calls, and he whom He calls, beholds Him that called him. He who beholds God is adopted into the rights of divine birth, and then at length as the son of God is delighted with the riches of the heavenly kingdom. The first then begins, the last is perfected.”