On the authority of Zayd ibn Khālid al-Juhanī, who said: The Messenger of Allah (peace and blessings be upon him) said: "Whoever gives food to a fasting person to break his fast will have a reward like theirs, without that diminishing anything from their rewards." (1)

1747 — Hishām ibn ʿAmmār narrated to us, Saʿīd ibn Yaḥyā al-Lakhmī narrated to us, Muḥammad ibn ʿAmr narrated to us, on the authority of Muṣʿab ibn Thābit, on the authority of ʿAbd Allāh ibn al-Zubayr, who said: The Messenger of Allah (peace and blessings be upon him) broke his fast at the home of Saʿd ibn Muʿādh, and said: "May the fasting people break their fast with you, may the righteous eat your food, and may the angels send blessings upon you." (2)

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(1) Its chain of transmission is authentic (ṣaḥīḥ) via the route of ʿAlī ibn Muḥammad — who is al-Ṭanāfisī — from his maternal uncle Yaʿlā — who is Ibn ʿUbayd al-Ṭanāfisī. The other two routes are weak: the first is due to Ibn Abī Laylā — who is Muḥammad ibn ʿAbd al-Raḥmān — for he was poor in memorization, and the second is due to Ḥajjāj — who is Ibn Arṭāh — for he was a mudallis who narrated without specifying his sources (ʿanʿana).
ʿAbd al-Malik: he is Ibn Abī Sulaymān, and Abū Muʿāwiyah: he is Muḥammad ibn Khāzim al-Ḍarīr, and ʿAṭāʾ: he is Ibn Abī Rabāḥ.
It was also recorded by al-Tirmidhī (818) and al-Nasāʾī in al-Kubrā (3317) via the route of ʿAbd al-Malik ibn Abī Sulaymān, and al-Nasāʾī (3316) via the route of Muḥammad ibn ʿAbd al-Raḥmān ibn Abī Laylā, both from ʿAṭāʾ ibn Abī Rabāḥ, from Zayd ibn Khālid. Al-Tirmidhī said: Ḥasan ṣaḥīḥ.
It is also in Musnad Aḥmad (17033) and Ṣaḥīḥ Ibn Ḥibbān (3429) and (4633).
It has supporting witnesses; see them in al-Musnad.

(2) Authentic due to other supporting evidence (ṣaḥīḥ li-ghayrihī), but this chain of transmission is weak due to the weakness of Muṣʿab ibn Thābit: he is the son of ʿAbd Allāh ibn al-Zubayr.
It was also recorded by al-Bazzār in his Musnad (2217), Ibn Ḥibbān (5296), and al-Khaṭīb al-Baghdādī in Mūḍiḥ Awhām al-Jamʿ wa al-Tafrīq 2/134 via the route of Muḥammad ibn ʿAmr ibn ʿAlqamah, with the same chain. =