‘And it came about that as they were parting from him, Peter said to Jesus, “Master, it is good for us to be here, and let us make three booths, one for you, and one for Moses, and one for Elijah”, not knowing what he said.'
The splendour of the scene so disoriented Peter that when he saw Moses and Elijah departing he cried out in disarray, “Master, it is good for us to be here, and let us make three booths, one for you, and one for Moses, and one for Elijah.” The reference to booths might have had in mind what was done on the Feast of Booths (Tabernacles) when booths were built for the seven day feast, a feast of joyous celebration of harvest, and of expectancy for the coming year, and having eschatalogical significance (Zechariah 14:16). He may have been thinking of setting up a permanent divine revelation here on the mountain, (men have always loved holy mountains). Or it may have been an attempt to prevent the two leaving by offering shelter so that they could continue with them for a while. This is suggested by the context, ‘as they were parting from Him'. Or his intention might have been to hide the unbearable glory. Or possibly he hoped that by retaining Moses and Elijah, both figures who testified to Jesus, together with Jesus Himself in His glory, people might come and worship there and come to a deeper knowledge of Who Jesus was, in the same way as they had. What a source of revelation that would be, Jesus, Moses and Elijah. All the religious questions that people had could be solved by impeccable sources. Whichever way it was it is clear that Peter recognised the huge value to him and his fellow disciples of what they were seeing and experiencing, to such an extent that he did not want it to end. Perhaps also he saw it as a way of keeping Jesus safe from the suffering He had mentioned. But we are specifically told that he did not know what he was doing. (He did not know what he was talking about). For by his intended actions he was putting Moses and Elijah on a par with Jesus, and that could not be, as God now made clear Peter was as impetuous as ever.
Again we have one of those indications of the genuineness of the story. No one in the early church would have invented something like this about Peter (compare Mark 9:4-6; Matthew 17:4).