Abu al-Haytham bin al-Tayyihan prepared a meal for the Prophet ﷺ and invited the Prophet ﷺ along with his companions. When they had finished eating, the Prophet ﷺ said, "Reward your brother."They asked, "Messenger of Allah, what is his reward?"He replied, "When a man enters someone's home, eats his food, and drinks his drink, and they then make supplication for him, that is his reward."
حدثنا محمد بن بشار حدثنا أبو أحمد حدثنا سفيان عن يزيد أبي خالد الدالاني عن رجل
صنع أبو الهيثم بن التيهان للنبي ﷺ طعاما فدعا النبي ﷺ وأصحابه فلما فرغوا قال أثيبوا أخاكم قالوا يا رسول الله وما إثابته قال إن الرجل إذا دخل بيته فأكل طعامه وشرب شرابه فدعوا له فذلك إثابته
No references are available.
[Its chain is daif] Abu Dawud alone narrated it. Abu Khalid Dalani used the form "an" without specifying direct transmission, and his situation was already discussed at 3756, and there was an unknown man in the chain.