Musnad Ahmad 31:444

'Abd al-Malik ibn 'Amr narrated to us, Zuhayr narrated to us, from Sharik ibn 'Abd Allah ibn Abi Namir, from 'Abd al-Rahman ibn Abi Sa'id al-Khudri, from his father, who said: We went out with the Messenger of Allah, peace and blessings of Allah be upon him, to Quba' on a Monday. We passed by the Banu Salim, and the Messenger of Allah, peace and blessings of Allah be upon him, stopped at the door of the Banu 'Utban. He called out, while Ibn 'Utban was upon the belly of his wife. He came out dragging his lower garment. When the Messenger of Allah, peace and blessings of Allah be upon him, saw him, he said: "We have hastened the man." Ibn 'Utban said: "O Messenger of Allah, what do you see regarding a man when he comes to his wife and does not emit [semen] upon her; what is upon him?" The Prophet, peace and blessings of Allah be upon him, said: "Verily, the water is from the water."