The Messenger of Allah ﷺ said, "Three supplications are never rejected: the supplication of a parent, the supplication of one who is fasting, and the supplication of a traveler."
قال رسول الله ﷺ: ثلاث دعوات لا ترد، دعوة الوالد، ودعوة الصائم، ودعوة المسافر.
Bayhaqi (3/345) and Diya in Mukhtarah (2057) both narrated it via Abu Abbas Muhammad bin Yaqub, who said, Ibrahim bin Bakr Marwazi narrated to us, who said, Sahmi Abdullah bin Bakr narrated to us, who said, Humayd Tawil narrated to us, from Anas bin Malik, and he mentioned it.Its isnad is hasan because of Ibrahim bin Bakr Marwazi, for his hadith is hasan. Ibn Jawzi says, "There are six men named Ibrahim bin Bakr, and we do not know any of them to be daif except this one," meaning Shaybani. Hafiz mentioned him in Lisan in the biography of Ibrahim bin Bakr Shaybani, and among them he mentioned Ibrahim bin Bakr Sahmi, meaning that he is not among the daif narrators.Also on this subject is what was narrated from Abdullah bin Amr bin As, who said that the Messenger of Allah ﷺ said, "Indeed the fasting person has, at the time of breaking his fast, a supplication that is not rejected."Ibn Majah (1753) narrated it from Hisham bin Ammar, who said, Walid bin Muslim narrated to us, who said, Ishaq bin Ubaydullah Madani narrated to us, who said, I heard Abdullah bin Abu Mulayka say, I heard Abdullah bin Amr bin As, and he mentioned it.Ibn Sunni (475) and Hakim (1/422), and from him Bayhaqi in Fadail Awqat (142), all narrated it via Hakam bin Musa, who said, Walid bin Muslim narrated to us, with his isnad, and they added, "And I heard Abdullah say at the time of breaking his fast, 'O Allah, I ask You, by Your mercy which encompasses all things, to forgive my sins.'"In it is Ishaq bin Ubaydullah, who is Ibn Abu Mulayka Qurashi Taymi Madani, also said to be Makki, who narrated from his brother Abdullah bin Abu Mulayka. The editor of the book Tahzib Kamal mentioned that he found, in the margins of the manuscripts, the author's words, "I think he is his brother."I say, this is the apparent view, and whoever said that he is Ishaq bin Ubaydullah bin Abu Muhajir Makhzumi, their freedman, brother of Ismail bin Ubaydullah, has erred. A number of narrators reported from him, but no one deemed him reliable except Ibn Hibban, so he is at the rank of acceptable, and his narration needs corroboration. As for Busiri, he graded it sahih.