Answer:
He mentions the poem by Robert Frost about "Nothing Gold can Stay" he recites it while looking at the sunset (or sunrise, I dont quite remember). He means to say it to how beautiful the sky looks but in other ways he can be saying it in gold "stay gold/ pure/ young" way as well. It also means to stay fresh, unspoiled, and pure, in a sense.
Explanation:
For example, by him saying "Stay gold" he can be saying he wishes to stay young and wants to value what he has now.
*I believe*
