Question: If I wanted to fast but was unable to wake up before the Adhhaan of the second Fajr, is it permissible for me to eat after the Adhhaan knowing that this is a supererogatory fast?
Response: If the situation is as you have stated, then do not eat or drink after the Adhhaan (of the second Fajr) so long as you wish to fast, even if your fast is a supererogatory one. If you were to eat after this Adhhaan, your fast would become nullified.
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 1, Page 198, Fatwa No.139.fatwaonline.com