No one knows. Jesus’ reasons for delay are not explained here. We can only surmise that a higher purpose-higher than saving people from physical death-caused Jesus not to go with immediate haste to His friend’s side. That purpose was surely the one that Jesus had come to fulfill: saving people from spiritual death, that is, from eternal separation from His loving heavenly Father.

Though Lazarus was raised miraculously, he did die later. So did Mary and Martha, the disciples, and all of Jesus’ closet friends. Jesus did not come to spare His loved ones the experience of physical death but to show them the path to eternal life.