What is the authenticity of the story of “Prophet Īsā (peace be upon him) and the three loaves of bread?”
This story has been recorded by Ibn Abi ad-Dunya in a few of his works viz. Az-Zuhd and Dham ad-Dunya. The narrator of this story is Laith bin Sulaim who is from Tābu‘ at-Tābi‘een i.e the generation after the Tabi’een .He however, did not attribute this narration to the Holy Prophet ﷺ but rather to himself, and most probably it is from the stories told by Christian Rabis.
The scholars of Islam have stated that the narrations from the Jews and Christian sources (Al-Isra’iliyaat) are of two categories:
1) Those that contradict the sacred texts i.e. The Holy Quran and the Traditions of the Holy Prophet ﷺ, such narrations are totally rejected and should not be transmitted.
2) Those that do not contradict the sacred texts. The ruling of such narrations is; it should not be relied upon nor should it be totally negated and condemned and also its transmission is permissible with the condition that it is not attributed to the Holy Prophet ﷺ.
After examining the wordings and context of this particular story, it does not appear to have any contradictions with our sacred texts rather it is of a supporting nature.
Therefore, it will be permissible to relate and transmit this story for purpose of spiritual motivation and encouragement, without attributing it to the Holy Prophet ﷺ and without firm conviction of its authenticity.
And Allah Ta’āla Knows Best
Mufti Kaleem Muhammad
Darul Iftaa, Jaamia Madinatul Uloom (Trinidad)
 الزهد لابن أبي الدنيا رقم الحديث 175 (ص: 83)
 ذم الدنيا رقم الحديث 87 (ص: 49)
 التاريخ الكبير للبخاري بحواشي محمود خليل (7/ 246)
لَيث بْن أَبي سُلَيم، أَبو بُكَير، الكُوفيُّ.
سَمِعَ مُجاهدًا، وطاوُوسًا، والشَّعبِيَّ.
قَالَ ابْن أَبي الأَسود، عَنْ أَبي عَبد اللَّه النَّخلِيّ: مات سَنَة إحدى، أو ثنتين، وأربعين ومئة
This answer was collected from Fatwa-tt.com, which is operated by the Darul Iftaa of Jaamia Madinatul Uloom (Trinidad and Tobago) under the advice and guidance of Mufti Ebrahim Desai (Daamat Barakaatuhum) of South Africa.