Praise be to Allah.
The fuqaha’ differed with regard to accepting the testimony of a woman with regard to sighting the new moon of Ramadan. There are two opinions:
1 – Her testimony may be accepted. This is the view of the Hanafis – if it is cloudy– and the Hanbalis, and it is one of the two views held by the Shaafa’is.
2 –That it cannot be accepted. This is the view of the Maalikis, and the more correct view according to the Shaafa’is.
Ibn Qudaamah said in al-Mughni (3/48):
If the one who brings the news is a woman, then according to the madhhab her word is to be accepted. This is the view of Abu Haneefah and is one of the two views held by the companions of al-Shaafa’i, because it is news that has to do with a religious matter, so it is akin to narration of reports, or telling people what the direction of the qiblah is, or that the time for prayer has begun. And it may be that it is not acceptable, because it is testimony about the sighting of the new moon, and the word of a woman cannot be accepted concerning that, like the new moon of Shawwaal. End quote.
See: Tabyeen al-Haqaa’iq (1/319), al-Taaj wa’l-Ikleel (3/278), al-Majmoo’ (6/286) and Kashshaaf al-Qinaa’ (2/304).
The Hanafis differentiate between cloudy and clear weather. If it is cloudy, the testimony of two men, or a man and two women, is acceptable, but if it is clear then it is essential to have many people to testify to that . See: al-Bahr al-Raa’iq (2/290).
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: Some scholars say that the testimony of a female cannot be accepted, either in Ramadan or at other times, because the one who saw the new moon at the time of the Messenger of Allah (peace and blessings of Allah be upon him) was a man, and because the Prophet (peace and blessings of Allah be upon him) said: “If two witnesses (shaahidayn) bear witness, then start the fast and end the fast,” and a woman is a shaahidah not a shaahid.
The evidence of our madhhab is that this is a report concerning a religious matter which is addressed equally to males and females, as males and females are equal with regard to narrating reports, and reports are religious matters. Hence they did not stipulate that sighting the new moon of Ramadan should be proven by a judge, and they did not stipulate any particular wording for the testimony, rather they said: If he hears a trustworthy person telling the people in his presence that he has seen the new moon, then he must fast on the basis of this news. End quote from al-Sharh al-Mumti’ (6/326).
As for the new moon of Shawwaal, it can only be proven by the testimony of two men.
And Allah knows best.