Narrated Ibn Abi Mulaika:

"There was a disagreement between them (i.e. Ibn `Abbas and Ibn Az-Zubair) so I went to Ibn `Abbas in the morning and said (to him), "Do you want to fight against Ibn Zubair and thus make lawful what Allah has made unlawful (i.e. fighting in Meccas?" Ibn `Abbas said, "Allah forbid! Allah ordained that Ibn Zubair and Bani Umaiya would permit (fighting in Mecca), but by Allah, I will never regard it as permissible." Ibn `Abbas added. "The people asked me to take the oath of allegiance to Ibn AzZubair. I said, 'He is really entitled to assume authority for his father, Az-Zubair was the helper of the Prophet, his (maternal) grandfather, Abu Bakr was (the Prophet's) companion in the cave, his mother, Asma' was 'Dhatun-Nitaq', his aunt, `Aisha was the mother of the Believers, his paternal aunt, Khadija was the wife of the Prophet (ﷺ) , and the paternal aunt of the Prophet (ﷺ) was his grandmother. He himself is pious and chaste in Islam, well versed in the Knowledge of the Qur'an. By Allah! (Really, I left my relatives, Bani Umaiya for his sake though) they are my close relatives, and if they should be my rulers, they are equally apt to be so and are descended from a noble family."

Chapter: The Statement of Allah: “...The second of two, when they (Muhammad ﷺ and Abü Bakr were in the cave, and he ﷺ said to his companion (Abu Bakr ) ‘Be not sad (or afraid), surely Allah is with us.'" (V.9:40)

📖 Sahih al-Bukhari — Sahih al-Bukhari 4665