Assalamu alikum a kaafir is maligning Islam by saying that it is mentioned in Tareekh Ibn Katheer vol 4 page 185 and Seerah Ibn Hisham, Ghzwa Banu Mustaliq that “Women are plentiful, and you can easily change one for another. Ask the slave girl; she will tell you the truth.” So the Apostle called Burayra to ask her and Ali got up and gave her a violent beating, saying, ‘Tell the Apostle the truth.’” The extra words "fa daraba darabun shadeedun" is mentioned in this variant, i want to ask is this authentic or not? because Ibn Hajar asqalani, Ibn Katheer did not comment on these words.
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Ibn Katheer actually reported this narration in Al-Bidaayah wan-Nihaayah and so did some other scholars who wrote about Islamic history such as Ibn Jareer At-Tabari in Taareekh Al-Umam wal Mulook. Both of them stated the narration of Ibn Is-haaq. Al-Haafith Ibn Hajar referred to it in Fat-h Al-Baari and did not comment on it. We did not find anyone who deemed that narration authentic or weak. The fact that it is mentioned in the books of history or that Al-Haafith Ibn Hajar did not comment on it does not mean that they deemed it authentic. They have stated it in the context of what happened in that story not to use it as a proof of any ruling.
The incident of Al-Ifk (a fabricated accusation against ‘Aa'ishah ) was mentioned fully in the two Saheeh books of Al-Bukhari and Muslim which are the soundest books after the Book of Allaah The Almighty. Neither of them mentioned that extra part, and Ibn Is-haaq is a controversial narrator of Hadeeth.
Allaah Knows best.
You can search for fatwa through many choices