I saw Ibn Umar grasp his beard and cut off whatever exceeded the width of his fist. He said, "When the Messenger of Allah ﷺ broke his fast, he would say, 'The thirst is gone, the veins are moistened, and the reward is secured, Allah willing.'"
رأيت ابن عمر يقبض على لحيته فيقطع ما زاد على الكف، وقال: كان رسول الله ﷺ إذا أفطر قال: ذهب الظمأ وابتلت العروق، وثبت الأجر إن شاء الله.
Abu Dawud (2357), Nasai in al-Kubra (3315), Daraqutni (2279), Hakim (1/422), and Bayhaqi (4/239) all narrated it from the hadith of Ali bin Hasan, who said, Husayn bin Waqid informed us, who said, Marwan al-Muqannaa informed us, and he related it. Daraqutni said, "Husayn bin Waqid narrated it alone, and its isnad is hasan."As for what has been reported that the Prophet ﷺ, when he broke his fast, would say, "O Allah, for You I have fasted, and upon Your provision I have broken my fast," there is some discussion regarding its isnad, and the discussion of it belongs in the book on fasting.