Abbas and Abu Sufyan were with him, meaning the Prophet ﷺ. He addressed them and said, "Now the battle has grown fierce." Then he said, "Call out, Companions of Surah al-Baqarah!"
حدثنا سفيان قال سمعت الزهري مرة أو مرتين فلم أحفظه
كان عباس وأبو سفيان معه يعني النبي ﷺ قال فخطبهم وقال الآن حمي الوطيس وقال ناد يا أصحاب سورة البقرة
Its isnad is sahih, and it is an abridgment of what came before it, but Sufyan bin Uyayna did not memorize it precisely from Zuhri. Likewise, Muslim narrated it from Ibn Abu Umar from Sufyan from Zuhri, and he alluded to it and said, "And he related the hadith," except that the hadith of Yunus and the hadith of Maamar are longer and more complete than it.