Matthew 17:2

μετεμορφώθη. ‘Was transformed.’ Here was a change (μετά) of μορφή, ‘the abiding form,’ ‘the manner of existence.’ μεταμορφοῦσθαι ‘involves an inwardness of change, a change not external, not of accidents, but of essence.’ Trench, N.T. Syn. Part II. p. 87. μετασχηματίζειν denotes change of external appearance. See Romans 12:2 and Philippians 2:6-8, where see Bp Lightfoot’s notes and separate note on μορφὴ and σχῆμα.

St Luke records that the change took place ἐν τῷ προσεύχεσθαι αὐτόν.

ὡς ὁ ἥλιος … ὡς τὸ φῶς. A hint that the Transfiguration took place at night, which is also rendered probable by the statement of St Luke that the three Apostles were ‘heavy with sleep,’ that they ‘kept awake,’ that they descended ‘the next day,’ ch. Matthew 9:32; Matthew 9:37.