Sforno on Leviticus 16:34/ספורנו על ויקרא ט״ז:ל״ד

1והיתה זאת לכם לחקת עולם לכפר, that the very day itself has the power to confer atonement even when there is neither a Temple nor a Temple service. In the words of our sages (Yuma 86) “repentance suspends the imposition of retribution and the arrival of the date of the Day of Atonement completes the atonement.”