Luke 9:33

33 Then it happened, as they were parting from Him, that Peter said to Jesus, "Master, it is good for us to be here; and let us make three tabernacles: one for You, one for Moses, and one for Elijah"--not knowing what he said.

Luke 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)

Luke 9:33 In-Context

31 who appeared in glory and spoke of His decease which He was about to accomplish at Jerusalem.
32 But Peter and those with him were heavy with sleep; and when they were fully awake, they saw His glory and the two men who stood with Him.
33 Then it happened, as they were parting from Him, that Peter said to Jesus, "Master, it is good for us to be here; and let us make three tabernacles: one for You, one for Moses, and one for Elijah"--not knowing what he said.
34 While he was saying this, a cloud came and overshadowed them; and they were fearful as they entered the cloud.
35 And a voice came out of the cloud, saying, "This is My beloved Son. Hear Him!"
Scripture taken from the New King James Version. Copyright © 1982 by Thomas Nelson, Inc. Used by permission. All rights reserved.