Musnad Ahmad 33:471

Yunus ibn Muhammad narrated to us, 'Abd al-Wahid ibn Ziyad narrated to us, Muhammad ibn Ishaq narrated to us, from Dawud ibn al-Husayn, from Waqid ibn 'Abd al-Rahman ibn Sa'd ibn Mu'adh, from Jabir, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "If one of you proposes to a woman, if he is able to look at that which invites him to marry her, then let him do so." He said: "So I proposed to a young woman from Banu Salama, and I used to hide for her behind a palm trunk until I saw of her some of what invited me to marry her, so I married her."