Musnad Ahmad 289:10

'Abd al-Razzaq narrated to us, he said: Sufyan informed us, from Ya'la ibn 'Ata, from Abu Razin Laqit, from his paternal uncle, in a raised (marfu') form, he said: The Prophet, peace and blessings of Allah be upon him, said: "The vision of the believer is one part of forty parts of prophethood." I am in doubt whether he added: "The vision of the believer is upon the leg of a bird as long as he does not speak of it; but if he speaks of it, it falls."