Jesus answered fear with a plain fact: a day has its set hours. Barnes explains that "The Jews divided the day from sunrise to sunset into twelve equal parts." Jesus used that fact to speak of His own life. Barnes calls the passage figurative and says that probably Jesus meant "there was an allotted or appointed time for him to live and do his Father's will," so that "He had nothing to fear, therefore, in Judea from the Jews, until it was the will of God that he should die." Gill reads it the same way: "as yet it was day with him, his time of life was not expired." The question invites the disciples to reason it through themselves instead of simply being told.

Jesus answers His own question: "If any man walk in the day, he stumbleth not, because he seeth the light of this world. But if a man walk in the night, he stumbleth, because there is no light in him" (John 11:9-10). The disciples raise no further objection about the danger. After Jesus tells them plainly that Lazarus is dead, Thomas says, "Let us also go, that we may die with him" (John 11:14-16), and they go. When Jesus arrives, Lazarus has lain in the grave four days (John 11:17).

Days were counted from sunrise to sunset in twelve parts, as Barnes notes, so "twelve hours" meant the whole working day of daylight. Barnes explains "the light of this world" as the light by which the world is lit, the light of the sun. A traveler in daylight could see the road; at night, without a lamp, he could not.

Jesus had used the same picture before healing the man born blind: "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).

This question shows that Jesus' life ran on His Father's schedule, not His enemies'. John has already said twice that no man laid hands on Him, "because his hour was not yet come" (John 7:30; John 8:20). The disciples counted the danger; Jesus counted the hours the Father had given.

Matthew Henry draws a wider lesson. If a man sets "the will of God before him as his rule," he does not hesitate, "but, walking uprightly, walks surely, and with a holy confidence." The point is not that danger disappears. It is that the one who walks in God's light and God's time does not stumble.