بسم الله الرحمن الرحيم
(Fatwa: 683/550/D=8/1438)
No problem, if it was uttered unintentionally. It is enough to make taubah from it. It is not a sentence of kufr. It also did not have any effect on the nikah, so worry not. It is recorded in one Hadith:
من نام عن صلوة او نسيها فليصلها اذا ذكرها .
If anyone of you forgets a prayer or sleeps and misses it, let him pray it when he remembers it.
ليس التفريط فى النوم انما التفريط فى اليقظة .
There is no sin in sleep, it is only when one is awake.
It means that if a man misses salah when he is awaken intentionally then it is sin. But if by chance he slept and could not wake at the time of salah due to which his salah was missed then it is not sin rather it is forgiven provided he has not developed the habit of sleeping till late and has arranged alarm etc for waking up at the time of salah.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband