Shiva Purana

siva.sh/siva-purana/vishweshwara-samhita/24/60

पैशुन्यं कूटवादश्च साक्षिमिथ्याभिलाषिणाम् । एवमादीन्यसंख्यानि पापानि विविधानि च। सद्य एव विनश्यंति त्रिपुंड्रस्य च धारणात् 1.24.६०।

sanskrit

Backbiting, false accusations, desiring false testimony, and other such sins are instantly destroyed by the wearing of the Tripundra (three marks of ash) on the forehead.

english translation

paizunyaM kUTavAdazca sAkSimithyAbhilASiNAm | evamAdInyasaMkhyAni pApAni vividhAni ca| sadya eva vinazyaMti tripuMDrasya ca dhAraNAt 1.24.60|

hk transliteration by Sanscript