Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 118

לשלם השוגג במעילה מה שמעל לה' ולהוסיף חומש, שנאמר: "וְאֵת אֲשֶׁר חָטָא מִן הַקֹּדֶשׁ יְשַׁלֵּם" (ויקרא ה, טז).

For a person who unintentionally makes use of a sacred object to make restitution for what he misused [when] sinning against God, and for him to add one fifth of its value, as [Leviticus 5:17] states: "For that which he sinned, [using something] sacred, he shall pay...."