Тосефта к Шмот 32:31

At what point [in the Yom Kippur service] does he say [the confession]? After the tefillah (i.e., the Amidah), and the one who passes before the ark says it during the fourth [blessing]. Rabbi Meir says, he prays seven [blessings] and concludes with the confession, and the Sages say, he prays seven and if he wants to conclude with the confession, he concludes, and he needs to specify the sins [for which he seeks atonement], the words of Rabbi Yehuda ben Beteira, as it is said (Ex. 32:31), "Alas, this people is guilty of a great sin [in making for themselves a god of gold]." Rabbi Akiva says, he does not need [to specify the sins]. In that case, why does it say, "in making for themselves a god of gold"? Rather, thus said the Place, "Who caused them to make themselves a god of gold? It is I, who gave them gold in abundance."