Muhammad ibn Ali ibn Mahziyar said:
I saw Abu Ja’far al-Thani عليه السلام (the Second), peace be upon him, spit in the ‘Sacred Mosque’ (al-Masjid al-Haram) between the Yemeni Corner and the Black Stone, and Imam عليه السلام did not bury it.
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 3, p. 283