Reference: al-Muntaqaa min Fataawa Shaykh Saalih al-Fowzaan – Volume 5, Page 160, Fatwa No.240
Question: I made the intention to perform the ‘Umrah for my eldest brother since he has passed away, so I want to know, is this act from the religious acts which (whose reward) will reach the deceased?
Response: Yes, because this is something good, [that being] you performing the ‘Umrah on behalf of your deceased brother whether it be the obligatory [‘Umrah] or the recommended (voluntary) [‘Umrah] – so this is a great act; However, [the permissibility of this is] based upon the condition that you have already performed the obligatory ‘Umrah for yourself first, and Allaah is the Most Knowledgeable.