More on advance payments... Where the product has to already be in one's tradition (in contrast to gourds, for example, that still need to grow). Plus, a specified amount as an advance discount that isn't used immediately is later considered interest. Also, a new mishnah! One who borrows money from another cannot allow the lender to stay in his courtyard, for example, lest it smack of interest (with some exception, based on the circumstances).