Both sentences mean the same thing. They are combined to emphasize that Jesus taught the crowds only with parables. (See: [[rc://en/ta/man/translate/figs-parallelism]])
"he taught them nothing except by parables." The double negative can be expressed in a positive way. AT: "everything he taught them he said in parables" (See: [[rc://en/ta/man/translate/figs-doublenegatives]])
This can be stated in active form. AT: "he made come true what God told one of the prophets to write long ago" (See: [[rc://en/ta/man/translate/figs-activepassive]])