98 Grk “And as.” Here καί (kai) has not been translated because of differences between Greek and English style.
99 Here the preposition ἐν (en) plus the dative articular aorist infinitive has been translated as a temporal clause ( ).
100 Or “the appearance of his face became different.” In 1st century Judaism and in the NT, there was the belief that the righteous get new, glorified bodies in order to enter heaven (1 Cor 15:42–49; 2 Cor 5:1–10). This transformation means the righteous will share the glory of God. One recalls the way Moses shared the Lord’s glory after his visit to the mountain in Exod 34. So the disciples saw the appearance of his face transformed, and they were getting a sneak preview of the great glory that Jesus would have (only his glory is more inherent to him as one who shares in the rule of the kingdom).
101 Or “became bright as a flash of lightning” (cf. ἐξαστράπτω); or “became brilliant as light” (cf. λευκός 1).

In other versions

And as he was praying, the appearance of his face was altered, and his clothing became dazzling white.

As he was praying, the appearance of his face changed, and his clothes became as bright as a flash of lightning.

As he was praying, the appearance of his face changed, and his clothes became dazzling white.

And as he was praying, the appearance of his face was transformed, and his clothes became dazzling white.

And as he was praying, the appearance of his face became different, and his clothing became white, gleaming like lightning.

And as he prayed, the fashion of his countenance was altered, and his raiment was white and glistering.

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