Jesus is either referring to a part of His conversation with Martha that is not recorded or He is speaking of His challenge for faith in her in verses #25-26 combined with the promised results which He had spoken to a messenger in John 11:4 to pass on to her.

John 11:25-26  Jesus said to her, “I am the resurrection and the life. He who believes in me will live, even though he dies;  and whoever lives and believes in me will never die. Do you believe this?”

John 11:4  When he heard this, Jesus said, “This sickness will not end in death. No, it is for God’s glory so that God’s Son may be glorified through it.”

His words are a summons to faith and a promise to those who do believe. All of those present were going to see a spectacular miracle, but only those who believed would see the significance of it. Only they would see the glory of God.

What is the glory of God? The Greek word translated here as “glory” is doxa which literally means a good opinion or view of someone or something. God’s glory is the good opinion we have of Him from having caught a glimpse of His splendour, magnificence, excellence, preeminence, dignity, grace, and majesty. It is a view which of necessity must result in praise and honour toward God just because of Who He is.

The raising of Lazarus was going to bring glory to Jesus and thus to God because those who believed would see the significance of this awesome deed, some of it now but even more of it after Jesus was Himself raised from the dead on the third day.