Sayyiduna Mikhnaf bin Sulaym (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) addressed us at Arafah and said: "Upon every Muslim household a sacrifice (udhiyah) and an 'atirah are obligatory. Do you know what the 'atirah is? It is the one you call the Rajabiyyah."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17869