1. Taking pay to examine bechoros

The next Mishnah states: הנוטל שכר להיות רואה את הבכורות – if one takes payment to examine bechoros for blemishes, אין שוחטין על פיו – we cannot shecht them based on his ruling, because he might permit the bechor in order to receive payment, אא"כ היה מומחה – unless he is an expert like אילא in Yavneh (a pious and reliable person), whom the Chochomim permitted to take four issars to examine a בהמה דקה, and six for a בהמה גסה (which requires more effort). The Mishnah concludes that he takes payment whether the animal was ruled a תם or בעל מום, because if he would only receive pay for ruling a bechor blemished, אתי למיחשדיה – [people] will come to suspect him that he only ruled it a בעל מום to receive payment. The Gemara asks that perhaps people will suspect that one who rules the bechor unblemished is only doing so in order to receive payment a second time, and answers that he may only receive payment once for examining any given bechor.

1. הנוטל שכרו לדון (מה אני בחנם אף אתם בחנם / taking a fee to do הזאה)

The next Mishnah states: הנוטל שכרו לדון – if one takes his pay for judging, דיניו בטילים – his rulings are void; for testifying, his testimonies are void; for sprinkling or being mekadesh מי חטאת, the water and ashes are disqualified. This is derived from where Moshe said: ראה למדתי אתכם וגו' – See, I have taught you, etc., teaching: מה אני בחנם אף אתם בחנם – just as I was taught Torah by Hashem for free, so too, you were taught Torah by me for free, and you must do the same. [A Baraisa adds שאם לא מצא בחנם שילמד בשכר – that if one did not find someone to teach him for free, he should learn from someone with payment, because a passuk says אמת קנה – purchase truth.] The Mishnah taught that one may receive compensation for losses incurred through performing these mitzvos, e.g., an old man who required transportation. It concludes: ונותן לו שכרו כפועל – and he may give him his fee as a laborer. A Baraisa says this means כפועל בטל – like an idle laborer, meaning כפועל בטל של אותה מלאכה – he is compensated like a laborer remaining idle from that specific work which he did not do in order to perform the mitzvah.

1. Purchasing from someone suspected regarding bechoros, shemittah, or terumah

The next Mishnah states: החשוד על הבכורות – if one is suspected regarding bechoros (to inflict them with blemishes), we may not purchase even deer meat from him, because it can be confused with calf meat (and might be a bechor), nor עורות שאינן עבודים – untanned hides. Tannaim debate if purchasing female hides is permitted. We may not purchase wool from him, but we may purchase spun thread and woolen garments. The Gemara infers that we may purchase tanned hides from him, because if the hide were of a bechor, לא הוה טרח ביה – he would not have troubled to tan it, reasoning: אי שמעו ביה רבנן מפסדו לי מינאי – if the Rabbis hear about it, they will confiscate it from me. [Purchasing spun thread and garments is permitted for the same reason.] The next two Mishnayos discuss what may or may not be purchased from one who is suspected regarding shemittah (i.e., of planting during shemittah, or doing business with produce which grew by itself), or is suspected of selling terumah as chullin.