[Machine] The Messenger of Allah ﷺ said, "A good dream is from Allah, and a bad dream is from Satan. So if anyone of you sees a dream that he dislikes, let him spit to his left three times and seek refuge in Allah from Satan, for it will not harm him."  

قَالَ رَسُولُ اللَّهِ ﷺ «الرُّؤْيَا الصَّالِحَةُ مِنَ اللَّهِ وَالْحُلْمُ مِنَ الشَّيْطَانِ فَإِذَا حَلَمَ أَحَدُكُمْ حُلْمًا يَخَافُهُ فَلْيَبْصُقْ عَنْ شِمَالِهِ ثَلَاثَ مَرَّاتٍ وَلْيَتَعَوَّذْ بِاللَّهِ مِنَ الشَّيْطَانِ فَإِنَّهَا لَا تَضُرُّهُ»  

I used to see (such horrible dreams) that I fell ill. I saw Abu Qatada who also said: I used to see dreams which made me sick until I heard Messenger of Allah ﷺ as saying: Good dreams are from Allah, so if any one of you sees which he likes he should not disclose it to one but whom he loves, but if he sees something which he does not like he should spit on his left side thrice and seek refuge with Allah from the mischief of the Satan and its mischief (i.e. of the dream), and he should not relate it to anyone, then it would not harm him. (Using translation from Muslim 2261g)  

وَأَنَا إِنْ كُنْتُ لَأَرَى الرُّؤْيَا تُمْرِضُنِي حَتَّى سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ «الرُّؤْيَا الصَّالِحَةُ مِنَ اللَّهِ فَإِذَا رَأَى أَحَدُكُمْ مَا يُحِبُّ فَلْيَحْمَدِ اللَّهَ وَلَا يُحَدِّثْ بِهَا إِلَّا مَنْ يُحِبُّ وَإِذَا رَأَى مَا يَكْرَهُه فَلْيَتْفُلْ عَنْ يَسَارِهِ ثَلَاثًا وَلْيَتَعَوَّذْ بِاللَّهِ مِنْ شَرِّهَا وَلَا يُحَدِّثْ بِهَا أَحَدًا فَإِنَّهَا لَنْ تَضُرَّهُ»