οἱ δὲ ἰδόντες αὐτὸν ἐπὶ τῆς θαλάσσης περιπατοῦντα ἔδοξαν ὅτι φάντασμά (ghost) ἐστιν.

οἱ δὲ ἰδόντες αὐτὸν ἐπὶ τῆς θαλάσσης περιπατοῦντα ἔδοξαν

ὅτι φάντασμά (ghost) ἐστιν.

And the ones who beheld him walking around on the sea thought that he was a ghost.