As with most of them, this is a pretty loose translation:
And why do we mention the words of [the sages] Shammai and Hillel [even] when their opinions are not accepted [as part of the final legal ruling]? To teach the generations to come that a person should not be too attached to his own words, for behold, the fathers of the [aka our] world weren’t very attached to their words [that is, acknowledged when the law didn’t rule in their favor, acknowledged that sometimes their ideas weren’t the best ones in the picture, etc.]
Mishnah Eduyot 1:4