Reference for Yoma 174:13
ומי אמר רב הכי והאמר רב הלכה כדברי האומר תפלת ערבית רשות לדברי האומר חובה קאמר
and then makes the confession, in the morning prayer one reads seven [benedictions] and makes confession, at Musaf one reads the seven [benedictions] and makes confession, at Minhah one reads the seven [benedictions] and makes confession, and at Ne'ilah one reads the seven [benedictions] and makes confession?<span class="x" onmousemove="('comment',' This contradicts Samuel's opinion.');"><sup>16</sup></span> [And further was]<span class="x" onmousemove="('comment',' [So emended by Ronsburg, v. Marginal Glosses; cur. edd. This is a point of dispute between Tannas, v. note 8].');"><sup>17</sup></span> it taught: On the Day of Atonement as it becomes dark one reads the seven benedictions and makes confession, and concludes with the confession<span class="x" onmousemove="('comment',' [I.e., he ends the middle benedictions of the 'Amidah with the usual formula, Blessed art Thou O Lord . . Who forgivest (Rashi) .]');"><sup>18</sup></span>