[16].Surah An-Nahl [The Bees] : Ayat 105

Ayat 105. It is only those who believe not in the Ayat (proofs, evidences, verses, lessons, signs, revelations, etc.) of Allah, who fabricate falsehood, and it is they who are liars.

Ayat 106. Whoever disbelieved in Allah after his belief, except him who is forced thereto and whose heart is at rest with Faith but such as open their breasts to disbelief, on them is wrath from Allah, and theirs will be a great torment.

Hazrat Ibn Umar (May Allah be pleased with them) reported: The Messenger of Allah [SAWW](PBUH) as saying: "The worst of lies is to pretend to have seen something which he has not seen.''  

[Al-Bukhari Book 09, Chapter 87, Hadith # 167]. 

Lesson : as mentioned above in Surah An-Nahl Ayat 105.who fabricate falsehood, and it is they who are liars. This Hadith strongly condemns falsehood, whether it relates to a dream or to the real world. It is a great sin in both cases.