Or HaChaim on Numbers
לחדש הזה, of this month, etc. The word "this" appears superfluous. Torat Kohanim Leviticus 23,6 explains that the word is used to teach us that on the Sukkot festival one need not eat matzah. Matzah needs to be eaten only on Passover. I have already explained this on Leviticus 14,7.