Musnad Ahmad 32:530

Abu Salamah al-Khuza'i narrated to us, Layth ibn Sa'd narrated to us, from Yazid ibn al-Had, from 'Amr ibn Abi 'Amr, from Anas ibn Malik, who said: I heard the Messenger of Allah (peace and blessings of Allah be upon him) saying: "I am indeed the first of the people..." He then mentioned its meaning, except that he said: "Just as the seed remains."