Chapter on the Rulings of Khitba (the Marriage Proposal)
The Prophet, peace and blessings be upon him, said: “When any one of you proposes to a woman and finds that he is able to look at something of her that may encourage him to marry her, let him do so.” Reported by Ahmad and Abu Dawud. In another narration he said: “Look at her, for that is more likely to create lasting harmony between the two of you.”
This indicates permission to look at whatever customarily appears of the prospective bride, provided that it is done without her knowledge and without being alone with her.
The jurists have said: “It is permissible for a man who intends to propose to a woman and is reasonably confident of her acceptance to look at what ordinarily shows of her body, without seclusion, so long as he is safe from temptation.” End quote.
In the hadith of Jabir it is related: “I used to hide so that I could observe her until I saw something of her that inclined me to marry her.”