וְנֽוֹדְעָה֙ הַֽחַטָּ֔את אֲשֶׁ֥ר חָטְא֖וּ עָלֶ֑יהָ וְהִקְרִ֨יבוּ הַקָּהָ֜ל פַּ֤ר בֶּן־בָּקָר֙ לְחַטָּ֔את וְהֵבִ֣יאוּ אֹת֔וֹ לִפְנֵ֖י אֹ֥הֶל מוֹעֵֽד׃
I poznanym by został grzech, którym zgrzeszyli: przyniesie wtedy zgromadzenie młodego cielca na ofiarę zagrzeszną, a sprowadzą go przed przybytek zboru.
Ibn Ezra
When the sin will be disclosed This rule also applies to the High Priest: as long as he does not realize his sin, and as long as he is not informed, he does not bring the bullock sin-offering. The reason why this rule — When the sin becomes disclosed — is mentioned first here, regarding the Sanhedrin, is that the High Priest is likely to inform them of their error, whereas no one is likely to inform the High Priest; he himself must become aware of his error. The sin-offering of the Assembly is identical in all details to the sin-offering of the High Priest. Thus, the High Priest is equal in stature to all Israel.
Ramban
WHEN THE SIN WHEREIN THEY HAVE SINNED IS KNOWN [THEN THE ASSEMBLY SHALL OFFER A YOUNG BULLOCK …]. It is self-understood that they cannot offer a sin-offering until they know that they have sinned. [So why does Scripture mention it?] But it is a linguistic expression of the [Hebrew] language to say, “and when it becomes known to them that they have sinned, they should bring their offering.” Therefore He did not mention it [in Verse 3] in the case of the anointed priest, because there was no need for it. It is possible that [the reason why the verse says, when their sin wherein they have sinned is known, is not merely as a linguistic expression but to indicate] that the assembly is not obliged to bring this sin-offering unless they have definite knowledge of their sin but not if it is merely a doubt, as in the case of the suspensive guilt-offering.310The asham talui (suspensive guilt-offering) is brought in case of doubt about one of those major sins for which the penalty if committed wilfully is excision, and a sin-offering if committed unintentionally. This offering is called a suspensive guilt-offering. An example of a case of a doubt which calls for such an offering is the following. Suppose a person has before him two pieces of fat, one of which is Scripturally-forbidden food, and the other is permitted to be eaten, and he eats one of the two [whilst the other is eaten by another person or lost]. A doubt then arises in his mind as to whether the piece he has eaten was the permitted or the forbidden food. In such a case he must bring an offering so as to effect atonement, and this is called a suspensive guilt-offering. If it is later established that he ate the forbidden fat, he must then bring a sin-offering (See Maimonides, “The Commandments,” Vol. I, pp. 79-80). The point Ramban makes thus is that the verse before us teaches that the sin-offering of the assembly can be brought only when it is definitely confirmed that it has sinned [unintentionally], unlike the suspensive guilt-offering of the individual which is brought in case of doubt. Our Rabbis have interpreted,311Torath Kohanim, Vayikra Chobah 4:12; Horayoth 5a. [that the verse says, the sin … is known, to teach that] “if the court knew that they had given an [incorrect] decision [on one of two kinds of forbidden food, such as fat and blood, declaring that one of them may be eaten], but did not know which one it was that they permitted, [and the people had eaten both], I might think that the court is obligated to bring a sin-offering [as they usually are when they give an incorrect decision which the people followed]. Scripture therefore says, when ‘the’ sin wherein they have sinned is known — not when only the sinners are known.”312In that case “the sinners” are known [i.e., it is known that the majority of the people relied on the mistaken decision and ate one of the forbidden foods, under which circumstances the court usually must bring a sin-offering for their mistaken ruling]. The particular “sin,” however, is not known, since the court does not know which of the forbidden foods it was that they incorrectly ruled to be permitted. In such a case, this verse teaches us that they do not bring a sin-offering. Horayoth 7b. This is not mentioned in the case [of the sin-offering] of the anointed priest, since He said there: If the anointed priest shall sin so as to bring guilt on the people,313Above, Verse 3. thus declaring [the law of the sin-offering of] the anointed priest to be like that of the public.
Rabbeinu Bahya
והקריבו הקהל פר בן בקר לחטאת והביאו אותו לפני אהל מועד, “and the congregation is to bring a two year old bull as a sin-offering, and they shall bring it to the entrance of the Tent of Meeting.” The sin of original man, Adam, and that of the Jewish people in the desert had something in common; this is the reason that our sages were of the opinion that Adam offered a bull as his sin-offering. (Chulin 60). This is also the reason that our sages in Vayikra Rabbah 5,6 made a point of commenting that this is the reason it is the only sin-offering of which the Torah writes that it was to be brought at the entrance of the Tent of Meeting (verse 4). The matter may be understood by means of a parable. A king had a friend who had brought him a valuable gift. The king was so impressed that he told his friend to display it at the entrance to his palace for all to see what a valuable gift he had presented to his ruler.