Musnad Ahmad 589:1

Muhammad ibn Ja‘far Ghundar and Yahya ibn Zakariyya ibn Abi Za’idah narrated to us, they said: Hajjaj ibn Artah narrated to us, from Muhammad ibn Sulayman, from his paternal uncle—Ibn Abi Za’idah said: Sahl ibn Abi Hathmah—who said: I saw Muhammad ibn Maslamah pursuing a woman from the Ansar, wanting to look at her—Ibn Abi Za’idah said: Thubaytah bint al-Dahhak, wanting to look at her—so I said: "You are a companion of the Messenger of Allah, may Allah bless him and grant him peace, and you do this?" He said: I heard the Messenger of Allah, may Allah bless him and grant him peace, say: "If Allah casts into the heart of a man the proposal of a woman, there is no harm in him looking at her."