Narrated `Aisha: (the mother of faithful believers) Allah's Apostle saw some nasal secretions, expectoration or sputum on the wall of the mosque in the direction of the Qibla and scraped it off.
Hadith ReferenceSahih Bukhari / The Book of As-Salat (The Prayer) / Hadith: 407
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة