Abu Bakr said, "I was with the Prophet ﷺ in the cave when I saw the footprints of the polytheists. I said, 'Messenger of Allah, if any one of them were to lift his foot, he would see us.'"He replied, "What do you think of two whose third is Allah?"
حدثني أبو بكر قال: كنت مع النبي ﷺ في الغار، فرأيت آثار المشركين، قلت: يا رسول الله لو أن أحدهم رفع قدمه رآنا قال: ما ظنك باثنين الله ثالثهما.
Bukhari reported it in the Tafsir (4663), and Muslim in the Virtues of the Companions (2381), both from the hadith of Habban bin Hilal, who said, Hammam narrated to us, Thabit narrated to us, Anas narrated to us, and he mentioned it. The Messenger of Allah ﷺ and Abu Bakr stayed in the cave for three nights.