Musannaf Ibn Abi Shayba 33:1167

Waki' narrated to us, from Sufyan, from Zakariya, from Ibrahim, that he wept during his illness. So they said to him, "O Abu 'Imran, what makes you weep?" He said, "And how should I not weep when I am awaiting a messenger from my Lord to bring me glad tidings of either this or that?"