Musnad Abu Ya'la al-Mawsili 154:135

Amr ibn Muhammad al-Naqid narrated to us, Isma'il ibn 'Ulayyah narrated to us, from Ayyub, from Yahya ibn Abi Kathir, from Muhammad, from Ibn 'Umar and Ibn 'Abbas, that they both said: We heard the Messenger of Allah, may Allah bless him and grant him peace, saying upon the steps of his pulpit: "People must certainly cease abandoning the Friday prayers, or Allah will surely seal their hearts, and then they will certainly be among the heedless."