The World Federation One Stop Fiqh

Ruling 1600

If someone is junub on a night of the month of Ramadan and is certain or deems it probable that if he goes to sleep he will wake up before the time of ṣubḥ prayers, and if he wakes up but does not want to perform ghusl, and he goes back to sleep and does not wake up again before the time of ṣubḥ prayers, in such a case, he must complete the fast of that day and qaḍāʾ and kaffārah become obligatory on him. The same applies, based on obligatory precaution, if he is doubtful that he will perform ghusl after waking up.