Musnad Ahmad 288:16

Yazid ibn Harun narrated to us, Shu'bah ibn al-Hajjaj informed us, from al-Nu'man ibn Salim, from Ibn Abi Aws, from his grandfather Aws, who said: "I saw the Messenger of Allah (ﷺ) perform ablution and he washed his hands three times," meaning he washed his hands three times. I said to Shu'bah: "Did he put them into the vessel, or did he wash them outside of it?" He said: "I do not know."