must. Behind this small word is all the weight of scriptural prophecy and divinely ordained necessity (9:31; Luke 22:37; 24:7, 26, 44). Jesus’ predictions concerning His death and resurrection come out of His understanding of the Old Testament Scriptures.
suffer many things. The prediction of the suffering Messiah comes particularly from Is. 52:13–53:12. See also Zech. 9:9; 12:10; 13:7; and the Old Testament generally for the theme of the righteous sufferer.
elders. Lay members of the Sanhedrin, the court that governed Jewish affairs. The court was composed of elders, chief priests, and teachers of the law (the scribes).
chief priests. Jesus predicts that the wealthy high-priestly families who were affiliated with the Sadducees will be involved in His death.
after three days. See Hos. 6:2. This is also a conventional expression for a short period.