Musnad Abu Ya'la al-Mawsili 3:46

Ubayd Allah narrated to us, Yahya narrated to us, from Ibn Abi Dhi'b, from Ibn Abi Layla, my brother narrated to me, from my father, from Ali, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When one of you sneezes, let him say: 'Praise be to Allah, Lord of the worlds, in every state.' And let him say: 'May Allah have mercy upon you.' And let him say: 'May Allah guide you and rectify your state.'"