Musannaf Ibn Abi Shayba 33:256

Shababa narrated to us, he said: Shu'bah narrated to us, from 'Asim ibn 'Ubayd Allah, from 'Abd Allah ibn 'Amir, from Ibn 'Umar, who said: The head of 'Umar was upon my lap. He said, "Place it [down], woe to your mother." Then he said, "Woe to me, and woe to the mother of 'Umar, if my Lord does not forgive me."