John 8:57

The Jews did not understand Jesus’ meaning because they disregarded the possibility of His deity. To them it seemed ludicrous that Abraham could have seen Jesus’ day in any sense since millennia separated the two men. Evidently they chose 50 years old as a round number symbolic of the end of an active life (cf. Numbers 4:3). Jesus was obviously not that old since He began His public ministry when He was about 30 (Luke 3:23), and it only lasted about three and a half years. According to Hoehner’s chronology, Jesus would have been in His mid-thirties at this time. [Note: Hoehner, p. 143.]