Sayyidah Aishah (may Allah be pleased with her) said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever goes to a people for food without having been invited enters as a sinner and eats what is not lawful for him."
No one narrated it from Rawh bin al-Qasim except Yahya bin Khalid, and he is majhul (unknown), one of Baqiyyah's shaykhs; Baqiyyah also has another chain for it that is majhul (unknown). The hadith of Ibn Umar (may Allah be pleased with them both) suffices.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصداق / 14547