Zavim 5:5 - 5:6

הטמא על מקצת המשכב – the majority of a impure person on a minority of the lying bed [of a Zav], the lying bed is defiled. And similarly, the greater part of a ritually pure person on the lesser part of a defiled bed, the ritually pure person is defiled. But we are not concerned of the lesser part of bed defiled, since the majority of it is ritually pure and the majority that the impure sits upon it, for with the lesser part of the thing that the defilement enters, and with its lesser part it departs, as is taught in the concluding clause [in this segment of the Mishnah]: "נמצאת טומאה נכנסת לו ויוצאת ממנו בטומאתו"/”it turns out that uncleanness enters it and leaves it through its lesser part.”

מקצת הטמא על המשכב – since that it is the lesser part of the impure person, even though that he leans on all of the bed, the bed is pure, until the greater part of the person with flux/gonorrhea (i.e., the Zav) is carried upon it.

ומקצת טהור על המשכב – that is to say or the lesser part of the pure person even on the entire bed.

טהור – until the greater of the part of the ritual pure person leans upon it.

וכן ככר של תרומה – it is referring to the Mishnah above (see Tractate Zavim, Chapter 5, Mishnah 3) as it teaches in the Mishnah: "כל הנושא ונישא על גבי המשכב טהור חוץ מן האדם"/”Whatever carries and is carried on top of a bed is clean.” And even food of priest’s due/heave-offering, if it was carried on top of the bed and there is between them something that interposes, even if it is the most thin like [a piece of] paper and similar to it, they are not susceptible to receive ritual defilement from the bed, for it doesn’t defile others and is not susceptible to receive defilement through shaking/moving other than something that has the breath of life (i.e., a human).

ור' שמעון מטמא בזו – since its place is impure, it defiles through shaking/moving, even something that does not have the breath of life. But the Halakha is not according to Rabbi Shimon.

הנוגע בזב ובזבה וכו' – each of these are equivalent regarding their contact/touching to their carrying in that they defile a person to defile clothing, therefore, they are considered a primary source of ritual defilement all the while that they didn’t separate from them, for after [being in contact] it defiles clothing, and therefore, a person who touches it makes himself first remove (i.e., first-degree of ritual impurity) and second remove and invalidates/makes unfit heave-offering/priest’s due through third remove.

פירש – [he separates] from what defiles him, he is none other than a mere first-degree of ritual impurity and defiles something to make it second-degree of ritual impurity, and makes heave-offering/priest’s due unfit in the third remove.

ואחד המסיט, ואחד הנושא – and even though they do not touch, the man with a flux/gonorrhea and a woman with a flux and a menstruant woman are explicitly written, as it is written (Leviticus 15:31-32): “Such is the ritual concerning him who has a discharge, [concerning him who has an emission of semen and becomes impure thereby], and concerning her who is in menstrual infirmity, [and concerning anyone, male or female, who has a discharge, and concerning a man who lies with an impure woman],” but the leper and the woman who has given birth we derive from (Leviticus 15:32): "לזכר ולנקבה"/”and concerning anyone, male or female, who has a discharge,” [the word] "לזכר"/for the man – to include the leper and [the word] "לנקבה"/or female to include the woman who has given birth to a child.