Response: One who has a wet dream whilst fasting or in a state of ihraam for Hajj or 'Umrah has no sin upon him nor any expiation and this act will have no (negative) baring on his fast, Hajj or 'Umrah. He must perform the ghusl accorded to the major impurity if he excreted any sperm as a result.
And with Allaah lies all the success, and may Allaah send prayers and salutations upon our Prophet Muhammad (sal-Allaahu `alayhe wa sallam) and his family and his companions.
The Permanent Committee for Islaamic Research and Fataawa, comprising –
Head: Shaykh 'Abdul 'Azeez ibn Abdullaah ibn Baaz;
Deputy Head: Shaykh 'Abdur-Razzaaq 'Afeefee;
Member: Shaykh 'Abdullaah Ibn Ghudayyaan;
Member: Shaykh 'Abdullaah Ibn Qu'ood
Fataawa Ramadhaan – Volume 2, Page 442, Fatwa No.368;
Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-'Ilmiyyah wal-Iftaa. – Fatwa No.7790. fatwaonline.com