Question: There are conflicts about the beginning of lunar months in Muslim world. Saudi Arabia had announced the Eid Al-Adha as one day before the other countries in some of last years. If 'Hajj is Arafat', and Saudi Government is wrong, that means Waqfa of Arafat was not accomplished on the right time. Thus, the Pilgrimage will not be acceptable. Who will be responsible for this?
There are ongoing conflicts about the beginning of lunar months in the Muslim world. The reasons of the controversy and the real principle to determine the lunar months are explained on this link: https://www.islamandquran.org/common-mistakes/ramadan-festival.html
According to the information given on the link, the begining of the month must be determined by scientific calculations.
What if you live in a country that does not comply with this method to start or end the Ramadan? What if you are performing the Hajj?
Such a controversy would never cause the Waqfa of Arafat to be performed on two different days even if it was in the era of Proohet Muhammad (pbuh). Because, Prophet Muhammad (p.b.u.h.) had established the position Emir al-Hajj who was responsible for these duties. The Pilgrims must perform the waqfa on the date he determines. His decision ends such conflicts. The following hadith was narrated from the Prophet Mohammad (p.b.u.h.):
“Your fasts are on the days you fast, your Eid al-Fitr is the day you celebrate the Eid, your Arafat is the day you climb on Arafat, your Eid al-Adha is the day you slaughter your sacrifice.”
Accordingly, the time for Waqfa of Arafat is the time when the pilgrim community considers it is the time for Waqfa of Arafat.
It is related that Imam Mohammad had said:
” If a person sees the crescent with his own eyes and performs the Waqfa on the day he himself determines as Arafa (eve of Eid al-Adha), his waqfa would not be acceptable. He would have to perform waqfa once more at the same time as the Emir al-Hajj. Because, even though the collective day of waqfa was the actual pilgrimage day, it is considered as Arafa (eve of Eid al-Adha) for the pilgrims that perform waqfa together. It is not permissible to diverge about the time of Waqfa. Therefore, the standalone waqfa of that person would be null.  ”
To conclude, the Waqfa of pilgrims is fulfilled successfully and on time every year, because of these specific conditions.