They were troubled - They were afraid. The sight was remarkable. It was sufficient to awe them. In the dark night, amid the tumultuous billows appeared the form of a man. They thought it was a spirit an apparition. It was a common belief among the ancients that the spirits of people after death frequently appeared to the living.
Related Commentaries of Matthew 14:26
Matthew 14:26
26 And when the disciples saw him walking on the sea, they were troubled, saying, It is a spirit; and they cried out for fear.