Imam Al-Nawawi's Riyad-us-Saliheen
Chapter 231
The Merit of Providing something to the Person Observing Saum (Fasting) for breaking the Fast

1265. Zaid bin Khalid Al-Juhani (May Allah be pleased with him) reported: The Prophet (sallallaahu ’alayhi wa sallam) said, "He who provides a fasting person something with which to break his fast, will earn the same reward as the one who was observing the fast, without diminishing in any way the reward of the latter.''
[At-Tirmidhi].

1266. Umm `Umarah Al-Ansariyah (May Allah be pleased with her) reported: Once the Prophet (sallallaahu ’alayhi wa sallam) visited us and I served him some food. He (sallallaahu ’alayhi wa sallam) asked me to eat. I replied that I was observing (optional) fast. He (sallallaahu ’alayhi wa sallam) said, "When people eat by a person observing fast, the angels keep asking Allah's forgiveness for that person until they have had their fill.''
[At-Tirmidhi].

Commentary:  This Hadith tells us the merits of the person who is himself observing Saum but serves meals to others.

1267. Anas (May Allah be pleased with him) reported: The Prophet (sallallaahu ’alayhi wa sallam) came to visit Sa`d bin `Ubadah (May Allah be pleased with him) who presented bread and olive oil to him. The Prophet (sallallaahu ’alayhi wa sallam) ate it and said, "The observers of fast have broken their fast with you (this is the literal translation, but the meaning is: `May Allah reward you for providing a fasting people with food to break their fast'); the pious people have eat your food and the angels invoked blessings on you.''
[Abu Dawud].

Commentary:  The word "Aftara'' is informative in nature, but it is used in the sense of a prayer. Thus, what it denotes is "May Allah give you the reward of one who arranges for the Iftar (breaking the Saum) of somebody." Thus, it induces one to hospitality according to his means.