It says in Fataawa al-Lajnah al-Daa’imah (1/496): “A woman should not allow anyone to photograph her face whether for a passport or for any other purpose, because it (her face) is ‘awrah, and because the existence of pictures in passports and elsewhere is one of the causes of fitnah… unless that is the case of necessity.” 

Based on that, it may be said that if the purpose of the woman’s travel is da’wah, to call people to Allaah, then this is not something necessary that would make this action permissible. In many foreign countries women attend the mosques and Islamic centers and benefit from what the daa’iyahs are doing there . So there is no need for this woman to expose herself to fitnah or the risk of doing some haraam actions, especially since there is such a great need for da’wah in the country where she is living. So she should focus her da’wah efforts on the people around her, her sisters in faith. Perhaps Allaah will cause others to benefit from her. 

But if the reason is that the man is going out for the purpose of da’wah, and his wife is to accompany him, then the ruling varies according to the length of time that he will spend there. If he will be gone for a long time, then it is acceptable for him to take his wife with him so that he will be safe from temptation. But if it is only for a short time, then he should not take his wife with him, and if he fears that he will fall into temptation, then he should not go, rather he should occupy himself with da’wah in the place where he is living in his own country.

 We ask Allaah to help us all to do that which He loves and which pleases Him.

 And Allaah knows best.

 Shaykh Khaalid al-Sabt