49 Jesus’ authority over creation raised a question for the disciples about who he was exactly (Who then is this?). This verse shows that the disciples followed Jesus even though they did not know all about him yet.
50 This section in Mark (4:35–5:43) contains four miracles: (1) the calming of the storm; (2) the exorcism of the demon-possessed man; (3) the giving of life to Jairus’ daughter; (4) the healing of the woman hemorrhaging for twelve years. All these miracles demonstrate Jesus’ right to proclaim the kingdom message and his sovereign authority over forces, directly or indirectly, hostile to the kingdom. The last three may have been brought together to show that Jesus had power over all defilement, since contact with graves, blood, or a corpse was regarded under Jewish law as causing a state of ritual uncleanness.

In other versions

And they were filled with great fear and said to one another, “Who then is this, that even the wind and the sea obey him?”

They were terrified and asked each other, “Who is this? Even the wind and the waves obey him!”

And they were terrified and asked one another, “Who then is this? Even the wind and the sea obey him!”

The disciples were absolutely terrified. “Who is this man?” they asked each other. “Even the wind and waves obey him!”

And they were terribly frightened and began to say to one another, “Who then is this, that even the wind and the sea obey him?”

And they feared exceedingly, and said one to another, What manner of man is this, that even the wind and the sea obey him?

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