When Jesus heard that, he said,
This sickness is not unto death, but for the glory of God, that the Son of God might be glorified thereby.
All Commentaries on John 11:4 Go To John 11
John Chrysostom
AD 407
Observe how He again asserts that His glory and the Father's is One; for after saying of God, He has added, that the Son of God might be glorified.
This sickness is not unto death. Since He intended to tarry two days where He was, He for the present sends away the messengers with this answer. Wherefore we must admire Lazarus' sisters, that after hearing that the sickness was not unto death, and yet seeing him dead, they were not offended, although the event had been directly contrary. But even so they came to Him, and did not think that He had spoken falsely.
The expression that in this passage denotes not cause, but consequence; the sickness happened from other causes, but He used it for the glory of God.
