Tosefta על ביצה 39:7

It so happened with Hillel the Elder that he leaned his hands on the burnt offering in the Temple Courtyard, and the students of Beit Shammai joined together against him. [Seeking to avoid a confrontation,] he said to them, "You came and you saw that that she (i.e., the offering) is a female and we need to make her into a peace offering." He then engaged them with talk about other matters until they left, and immediately Beit Shammai gained the upper hand [over Beit Hillel], and they sought to establish the halacha according to their view. And among them was Bava ben Buta who was of the disciples of Beit Shammai, but he knew that the halacha was according to the words of Beit Hillel in every matter, and so he went and brought every sheep from Kedar, and stood them in the Temple Courtyard, and said, "Anyone who needs to bring a burnt offering or a peace offering may come and bring it." [And] they came and took the livestock and they offered them as burnt offerings, and leaned their hands on them. And it was on that day that the halacha was established to be according to the words of Beit Hillel, and no person challenged [Beit Hillel] on any matter. And later on, it so happened with one of the disciples of Beit Hillel who leaned his hands on a burnt offering in the Temple Courtyard, that one disciple among the disciples of Beit Shammai found him [and] said to him, "What is this leaning of hands?" [The disciple of Beit Hillel] said to him, "What is this silence?" (i.e., "Why are you not staying silent since the halacha has been established?"). [And thus] he silenced him with a rebuke.