Looking at a Woman Without Her Knowledge

Question :

Some of those seeking marriage request a picture of the young woman or to see her in person, or it is arranged for him to see her on some occasion when she is unaware of it. Is this permissible?

Answer:

It is not permissible for the suitor to be given a picture of the young woman, because of the dangers that includes.. He might play around with this picture, and the picture does not give a true likeness of the one photographed. How many times does a person see a picture and it is far from the true likeness of the subject? Also, the picture might show the woman when she is beautified and wearing make up, more than is natural, and so the husband is misled by her; then if he sees her and she does not look as she did in the picture, he may refuse her. So there will be a negative reaction to this wife.

As for looking at her in person or its being arranged for him to see her on some occasion without her knowing, there is no objection to this; indeed it is one of those things which is required, so that he may know what is his situation, however, there must be conditions attached to this:

The first is that he is not alone with her.

The second is that his looking be practical, not for pleasure and gratification.

The third is that he feels that he is most likely to accept, if she pleases him.

Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 5 Page 208