Mukhtasar Bukhari

Sayyiduna Abu Qatadah (may Allah be pleased with him) narrates that the Noble Prophet (peace and blessings of Allah be upon him) said: "A good dream is from Allah and a bad dream is from Satan. So when any of you sees a bad dream (a dream that frightens him), he should spit on his left side (three times) and seek refuge in Allah from its evil, then that (dream) will not harm him."