Allah Almighty says: {And of His signs is your sleep by night and day} [Al-Rūm: 23]
Dreams and visions fall under three categories:
First: Good pleasant dreams: This is when a person sees pleasant things in his sleep. It is glad tidings from Allah Almighty, and he can relate it to his loved ones.
Second: Unpleasant dreams: These come from Satan.
Third: Dreams with no specific interpretation: These stem from people’s inner thoughts, Satanic insinuations during sleep, or other causes.
838/1 - Abu Hurayrah (may Allah be pleased with him) reported: I heard the Prophet (may Allah’s peace and blessings be upon him) say: “Nothing of prophethood is left but glad tidings.” They said: “What are the glad tidings?” He said: “A good dream.” [Narrated by Al-Bukhāri]
1) Only a believer can have a good true dream, and someone else can have it for him. It is an honor from Allah Almighty to His pious servants, and it is deemed as advance glad tidings for them.
2) A good dream is affirmation and honor, and it does not entail any obligation.
839/2 - He also reported that the Prophet (may Allah’s peace and blessings be upon him) said: “When the (end of ) time draws near, the dream of a believer can hardly be false, and the dream of a believer is one part from forty-six parts of prophethood.” [Narrated by Al-Bukhāri and Muslim]
In another version: “The most truthful of you in their speech are those who have the truest dreams.”
1) When the Hour approaches and most knowledge is taken away, people will be compensated by true dreams.
2) The more a person is truthful, the purer his heart and the stronger his perception, and this state stays with him in his sleep and thus he only has true dreams.
840/3 - He also reported that the Prophet (may Allah’s peace and blessings be upon him) said: “Whoever sees me in a dream will see me when he is awake – or: it is as if he has seen me when he is awake – the devil does not take my shape.” [Narrated by Al-Bukhāri and Muslim]
1) Satan does not take the Prophet’s image, lest one would lie that he told him something during sleep.
2) Seeing the Prophet (may Allah’s peace and blessings be upon him) here means seeing his well-known image which is described in the books of the Prophet’s characteristics.
3) Seeing the Prophet (may Allah’s peace and blessings be upon him) is a sign of the dream’s trueness, if his appearance conforms with the description reported in the books on the Prophet’s biography.
841/4 - Abu Sa‘īd al-Khudri (may Allah be pleased with him) reported: I heard the Prophet (may Allah’s peace and blessings be upon him) say: “If anyone of you sees a dream that he likes, it is from Allah Almighty. He should praise Allah for it and relate it to others.” Another version reads: “He should narrate it only to those whom he loves. If he sees something else which he dislikes, it is from the devil. He should seek refuge with Allah from its evil and not mention it to anyone, for it will not harm him.” [Narrated by Al-Bukhāri and Muslim]
842/5 - Abu Qatādah (may Allah be pleased with him) reported that the Prophet (may Allah’s peace and blessings be upon him) said: “A good dream is from Allah, and a bad dream is from Satan. So, whoever sees (in a dream) something he dislikes, he should spit dryly to his left three times and seek refuge with Allah from Satan, for it will not harm him.” [Narrated by Al-Bukhāri and Muslim]
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843/6 - Jābir (may Allah be pleased with him) reported that the Prophet (may Allah’s peace and blessings be upon him) said: “If anyone of you has a dream that he dislikes, let him spit thrice on his left, seek refuge with Allah from Satan thrice, and turn to the other side.” [Narrated by Muslim]
1) A bad dream, in which a person sees unpleasant and disturbing things, comes from Satan. A good dream, on the other hand, is glad tidings to the believer, and it comes from Allah Almighty.
2) A bad dream does not harm a person if he does certain things: spitting dryly three times to his left side, seeking refuge with Allah three times from the evil of Satan and the evil of what he has seen in the dream, and turning to the other side. Moreover, if he feels active, he can get up, perform ablution, and pray. He should not relate the dream to anyone or try to interpret it. Whoever does these things will not be harmed by such dreams, Allah Willing.
844/7 - Abu al-Asqa‘ Wāthilah ibn al-Asqa‘ (may Allah be pleased with him) reported that the Prophet (may Allah’s peace and blessings be upon him) said: “From the gravest of lies is someone who ascribes himself to other than his biological father, or claims to have seen something in a dream which he has not actually seen, or ascribes something to the Messenger of Allah which he did not say.” [Narrated by Al-Bukhāri]
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1) Lying with regard to having a (good) dream is a lie with regard to Allah, and that is a major sin. Indeed, telling a lie concerning Allah is not like lies about people.
2) It is prohibited to tell lies with regard to the Prophet (may Allah’s peace and blessings be upon him), which, by extension, is considered lies about Allah Almighty, since the Prophet only spoke by divine revelation.
3) If a person lies and claims to have seen something in a dream, this is one of the worst types of falsehood. A believer should stick to the truth, for it is a means of salvation, and avoid lying, which leads to ruin.