After reminding Israel of the offerings they had to do on a daily, monthly, and annual basis in Numbers 28, it's only in verse 31 that the author mentions the quality of offerings needed:
"Be sure they are without blemish. You shall present them with their drink offerings, besides the regular burnt offering with its grain offering."
How come this emphasis was only in the portion of the Feast of Weeks offerings? Is there particular importance to the Feast of Weeks?