Whoever catches the Fajr Prayer in Muzdalifah, there is no Sin on him
Question :
A traveling caravan left from 'Arafat after sunset and they got lost. So, they headed towards Makkah and the police returned them to 'Arafat. Then, when they arrived there, they stopped and offered the Maghrib and "Isha' prayers. at 1:00 am at night. Then they entered Muzdalifah at the Athan of Fajr. So, they offered the Fajr prayer there in Muzdalifah and then left (for Mina). Is there any sin on them for that or not?
Answer:
There is no sin on these people because they caught the Fajr prayer in Muzdalifah when they entered at the time of the Athan of Fajr and offered the Fajr prayer there when it was dark. Indeed, it has been confirmed from the Prophet that he said:
"Whoever is present for this prayer of ours and he stands with us (in supplication and remembrance of Allah) until we leave, and before that he stood at 'Arafat during the night or the daytime, then he has completed his Hajj and completed his prescribed duties."
However, these people erred in delaying the prayer until after the middle of the night, because the time of the 'Isha' prayer is until the middle of the night, as is confirmed in Sahih Muslim from a Hadith of 'Abdullah bin 'Amr bin Al-'Aas from the Prophet.
Source:
Ash-Shaykh Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 4 Page 225