 The number of mishnayot is according to the standard numbering; however, different versions split up the individual mishnayot, or combine them, and the chapter breaks may vary, as well.Chapter One (nine mishnayot) deals with the prohibition of trade with idolaters around their festival (so as not to be complicit in the festivity), and the items that are forbidden to be sold to idolaters (which is basically any item that the idolater is likely to offer in an idolatrous service or commit an immoral act with).Thus, the main commandment explored in the chapter is lifnei iver, because a Jew who helps a gentile to worship idols is facilitating sin.