Musnad Abu Ya'la al-Mawsili 42:364

Zuhayr narrated to us, Ubayd Allah ibn Musa narrated to us, Shayban narrated to us, from Firas, from Atiyyah, from Abu Sa’id, from the Prophet of Allah, may Allah bless him and grant him peace, who said: "Avoid the supplications of the oppressed." And Atiyyah said: A man from the people of Khurasan said—and Abu Hurayrah said—: "There is no veil between them and Allah."