John Gill Commentary Mark 9:5

"And Peter answereth and saith to Jesus, Rabbi, it is good for us to be here: and let us make three tabernacles; one for thee, and one for Moses, and one for Elijah." — Mark 9:5 (ASV)

And Peter answered and said to Jesus
He addressed himself to him, as being more familiar with him; as also because he was the principal person: wherefore he says,

master, it is good for us to be here :
the company and conversation were exceeding agreeable to him and his fellow disciples; and the glory that Christ appeared in surpassed every thing they had seen before:

and let us make three tabernacles ;
or, as the Syriac, Arabic, and Ethiopic versions read, "and we will make" expressing not a petition, but a resolution; to which the Persic version premises, "if thou wilt give us commandment"; submitting it to the will of Christ:

one for thee, and one for Moses, and one for Elias ;
(See Gill on Matthew 17:4).