It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: When any one of you is praying, he should not spit in front of him or to his right side, but rather he should spit to his left side or under his foot.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 14470
Hadith Gradingحکم دارالسلام:صحيح لغيره، وأبو الزبير ثم يصرح بسماعه من جابر، أما ابن جريج فصرح بسماعه من أبى الزبير عند ابن حبان