It is narrated from Hazrat Muhammad bin Maslamah (may Allah be pleased with him) that I heard the Prophet (peace and blessings of Allah be upon him) say: If Allah creates in a person's heart the thought of sending a marriage proposal to a woman, then there is no harm in looking at her.
Hadith Referenceمسند احمد / مسند الشاميين / 17981
Hadith Gradingحکم دارالسلام:إسناده ضعيف لإبهام الرجل من أهل البصرة