"I must work the works of him that sent me, while it is day: the night cometh, when no man can work." (John 9:4)
It is striking how often the Lord Jesus used the term "must" in connection with the different aspects of the work He came to do. Since He is our example, we also must be serious and urgent about our Father's work. Even as a boy in the temple He told His parents, "I must be about my Father's business" (Luke 2:49).
Then early in His ministry, as He went from place to place, He said, "I must preach the kingdom of God to other cities also: for therefore am I sent" (Luke 4:43). Toward the end of His earthly ministry, He said one day, "I must walk to day, and to morrow, and the day following: for it cannot be that a prophet perish out of Jerusalem" (Luke 13:33). He also said to His disciples that "he must go unto Jerusalem, and suffer many things of the elders and chief priests and scribes, and be killed, and be raised again the third day" (Matthew 16:21).
He had told the great teacher of Israel, Nicodemus, "Ye must be born again." To explain how this could be, He then said, "And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up: That whosoever believeth in him should not perish, but have eternal life" (John 3:7, 14-15). Before we could ever be born again to everlasting life, therefore, Christ must be lifted up on the cross to die for our sins.
Still, all "the scriptures must be fulfilled" (Mark 14:49), and accordingly, "he must rise again from the dead" (John 20:9). Yet, even this did not fully complete "the works of Him that sent me," for Christ had said that "the gospel must first be published among all nations" (Mark 13:10). Therefore, we also must work the works of Him who sent us, before our days of opportunity are gone. HMM