I heard the Prophet ﷺ say, "On the Day of Resurrection, I will intercede and say, 'My Lord, admit into Paradise anyone who has even a mustard seed of faith in his heart.' So they will be admitted. Then I will say, 'Admit into Paradise anyone who has the smallest particle of faith in his heart.'"Anas said, "It is as though I can still see the fingers of the Messenger of Allah ﷺ."
سمعت النبي ﷺ يقول: إذا كان يوم القيامة شفعت. فقلت: يا رب أدخل الجنة من كان في قلبه خردلة، فيدخلون، ثم أقول: أدخل الجنة من كان في قلبه أدنى شيء. قال أنس: كأني أنظر إلى أصابع رسول الله ﷺ.
Bukhari narrated it in Tawhid (7509) from Yusuf bin Rashid, who said, Ahmad bin Abdullah narrated to us, who said, Abu Bakr bin Ayyash narrated to us, from Humayd, who said, I heard Anas, and he mentioned the hadith.