The Companions of Allāh’s Messenger – peace and blessings be upon him – used to say to each other when they met on ‘Eid:

Eid greeting

(taqabbalallāhu minnā wa minkum, which means ‘may Allāh accept from us and you [our fasts and deeds].’)

Al-Ḥāfidh Ibn Ḥajr, Fatḥ Al-Bārī, grades this narration’s chain of transmission ḥasan and cites it from Al-Maḥāmilīyyāt.