Sayyiduna Tariq bin Abdullah al-Muharibi (may Allah be pleased with him), one of the Companions of the Prophet (peace and blessings be upon him), narrates that the Messenger of Allah (peace and blessings be upon him) said to me: "When you pray, do not spit in front of you, nor to your right; rather, spit to your left if it is clear, or under your foot."
Hadith Referenceالمعجم الكبير للطبراني / باب الطاء / 8136