Aishah said: Each of us (wives of the Prophet) had only one clothe in which she would menstruate. Whenever it was smeared with blood, she would moisten it with her saliva and scratch it with saliva.
Hadith Referenceسنن ابي داود / كتاب الطهارة / 358
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:إسناده صحيح
358. Commentary: This applies in the case when there is only a minor stain, spot, or drop; if there is a larger amount, then it is obligatory to wash it thoroughly with water, as will be mentioned in the forthcoming ahadith.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 358