Divorce of Ibn ‘Umar When His Wife Was in Her Menses
13-8-2002 | IslamWeb
Question:
I have read in many books of Fiqh that Ibn Omar when he divorced his wife during her menses he was commanded to return her and divorce her when she was purified. Did that divorce count as one or not?
Answer:
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad 
is His slave and Messenger.
Divorcing a wife while in her menstruation period is forbidden and it is a divorce of innovation as mentioned in the Quran and Sunnah. The Muslim scholars agreed upon this ruling but they differ concerning whether or not this divorce is valid. The majority of the Muslim scholars, including the four Imams, are of the opinion that this divorce is valid.
Their evidence is the case of Ibn ‘Umar, may Allah be pleased with him. It is narrated in Al-Bukhari and Muslim that during the life of the Prophet ‘Abdullah ibn ‘Umar 
had divorced his wife while she was menstruating. ‘Umar ibn al-Khattab asked the Prophet about that. The Prophet said, “Order him (your son) to return her back (to wedlock life) and keep her till she is pure and then to wait till she gets her next period and becomes pure again, whereupon, if he wishes to keep her, he can do so, and if he wishes to divorce her, he can divorce her before having sexual intercourse with her, and that is the prescribed period which Allah has fixed for the women meant to be divorced.”
There is a narration in Al-Bukhari with the wording, 'It is considered a legal divorce.' Also, return her back means that there was a separation hence a divorce.
However, some scholars are of the opinion that such a divorce is not counted as a legal divorce. Among them are Ibn Taymiyyah, Ibn al-Qayyim 
. They based their opinion on some other narrations that read: “He did not count it (divorce) anything.” [Ahmad and Abu Daawood]
The opinion of the majority of the Muslim scholars that the divorce is valid is the preponderant one for the following two reasons:
A) The abundance of the narrations that prove the validity of such a divorce.
B) The narrations that prove the validity of this divorce are strong compared to the other narration, which suggest the opposite.
Therefore, the divorce given during menses is considered as one legal divorce.
For more benefit on the Sunni divorce and Bid‘i divorce, please refer to Fataawa 289207, 85415, 81864, 367312, 271282 and 378277.
Allah knows best.