(The narrator said:) I saw Muhammad bin Maslamah (may Allah be pleased with him) following Thubaytah bint al-Dahhak with his eyes in one of the quarters of Madinah, and I said to him: You do this? He said: Yes, I heard the Messenger of Allah (peace and blessings be upon him) say: "When Allah puts into a person's heart (the thought of) proposing marriage to a woman, there is no harm in his looking at her." Abu Mu'awiyah narrated it thus from al-Hajjaj, from Sahl bin Muhammad bin Abi Hathmah, from his paternal uncle Sulayman bin Abi Hathmah.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16553