Sayyiduna Hudhayfah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Whoever spits in the direction of the Qiblah will come on the Day of Resurrection in such a state that his spit will be between his two eyes."
Hadith Referenceصحيح ابن خزيمه / جماع أبواب الأفعال المكروهة فى الصلاة التى قد نهي عنها المصلي / 925