Komentaryo sa Levitico 15:23: Rashi, Ibn Ezra, Rashbam & Chizkuni

ואם על המשכב הוא AND IF ONE BE ON HER PLACE OF REPOSE [OR ON ANY THING WHEREON SHE SITTETH] — This means, one who sleeps or sits on the place where she has slept or has sat even though he does not directly touch it (e. g. if there are covers upon the couch or the seat; for if he touches it vv. 21 and 22 apply); he also comes under the law of uncleanness that is stated in the above verse — that he requires washing of garments.

if on the seat This refers to the abovementioned “utensil she sat upon” [:22]. The case is that of a utensil atop her seat, or a utensil atop another utensil. Thus, its ritual impurity is less severe. Scripture does not mention a saddle [see :9], because it speaks of things that are likely to occur; but the law in such a case would be the same.

'ואם על המשכב הוא וגו, if some sits or lies on something even indirectly in contact, מדרס, with the afflicted person chair or bed, etc., he will still become ritually contaminated by such indirect contact בנגעו בו יטמא עד הערב, even if the “contact” was so indirect as instead of sitting on the contaminated item one sat on a saddle supported by the contaminated item, the ritual impurity lasts until evening when immersion in a ritual bath removes it. He is then, however, not of a sufficiently severe degree of ritual impurity to contaminate clothing (even his own) over and beyond his body. In other words, in this kind of scenario the Torah did not add that he has to wash (immerse) his garments in order to become ritually pure again. (as it had done in verse 21 and 22, for instance)

על הכלי UPON A VESSEL — This is intended to add to משכב and מושב any article for riding on (Sifra, Metzora Parashat Zavim, Section 4 15).

בנגעו בו WHEN HE TOUCHETH IT — "it" (בו) — this refers only to מרכב which, as has just been stated, is included in the law on account of the words על הכלי.

בנגעו בו יטמא WHEN HE TOUCHETH IT HE SHALL BE UNCLEAN, but does not require washing of the garments, because so far as the מרכב is concerned its being touched does not communicate uncleanness to people so that they in turn should render their garments unclean (cf. Mishnah Kelim 23:3).