Hilchot Tshuva, Chapter 1, Halacha 3

OK, I'm experimenting with a new look for these Halachot which will hopefully make it easier to read.

הִלְכּוֹת תְּשׁוּבָה פֵּרֶק א

ג וְכֵן בַּעֲלֵי חַטָּאוֹת וַאֲשָׁמוֹת--בְּעֵת שֶׁמְּבִיאִין קָרְבְּנוֹתֵיהֶם עַל שִׁגְגָתָן אוֹ עַל זְדוֹנָן, אֵין מִתְכַּפֵּר לָהֶן בְּקָרְבָּנָם, עַד שֶׁיַּעֲשׂוּ תְּשׁוּבָה, וְיִתְוַדּוּ וִדּוּי דְּבָרִים: שֶׁנֶּאֱמָר "וְהִתְוַדָּה--אֲשֶׁר חָטָא, עָלֶיהָ” ויקרא ה,ה

Hilchot Tshuva, Chapter 1

And similarly, someone who brings a Chatat (sin offering) or Asham (guilt offering) – at the time that they bring their sacrifice, whether for an inadvertent sin or a deliberate sin, they are not atoned with the sacrifice unless they do Tshuva. And they must confess with a verbal confession as it is written “And they will confess that which they sinned” (Vayikra 5:5)