Lukas 9:33

33 And it came about, just as the men departed from Rebbe Melech HaMoshiach, Kefa said, Adoni, it is good for us to be here; let us make shalosh sukkot, one for you and one for Moshe Rabbeinu and one for Eliyahu HaNavi. (Kefa did not know what he was saying.)

Lukas 9:33 Meaning and Commentary

Luke 9:33

And it came to pass, as they departed from him
That is, as Moses and Elias departed from Christ; or "when they began to depart", as the Syriac version renders it; or "would depart", as the Arabic and Persic versions; seemed desirous of going, or made some signal or other by which the disciples perceived they were about to go; for, as yet, they were not gone;

Peter said unto Jesus, master, it is good for us to be here, let us
make three tabernacles, one for thee, and one for Moses, and one for
Elias; (See Gill on Matthew 17:4)

not knowing what he said,
nor "what to say", as Mark observes, being in a surprise, and not in a situation to consider and weigh things well, whether what he said was right and proper, or not; (See Gill on Matthew 17:4)

Lukas 9:33 In-Context

31 Who appeared in kavod and were speaking of Moshiach’s Litziat Exodus, which he was about to fulfill in Yerushalayim.

32 But Kefa and the ones with him had been weighed down with sleep. And having awakened fully, they saw his kavod and the two men standing with him.

33 And it came about, just as the men departed from Rebbe Melech HaMoshiach, Kefa said, Adoni, it is good for us to be here; let us make shalosh sukkot, one for you and one for Moshe Rabbeinu and one for Eliyahu HaNavi. (Kefa did not know what he was saying.)

34 And while Kefa was saying these things, an anan (cloud) came and was overshadowing them, and while they entered into the anan they were afraid.

35 And a bat kol came from the anan (cloud), saying ZEH BENI BECHIRI, ELAV TISHMAUN (This is my Son the Chosen One, listen to him. [YESHAYAH 42:1; TEHILLIM 2:7]