Volume 1, Book 8, Number 402:
Narrated Abd Huraira and Abu Said:
Allah’s Apostle saw some expectoration on the wall of the mosque; he took gravel and scraped it
off and said, “If anyone of you wanted to spit he should neither spit in front of him nor on his right
but he could spit either on his left or under his left foot.”
Volume 1 – 107 / 1700
SAHIH BUKHARI VOLUME 1 > BOOK 8: PRAYERS (SALAT)