Is it permissible for the da’wah office to take what is left over from a program to buy and distribute to the poor?
Question

                We are working in an office of da’wah, inviting different communities to Islam. We thought of making an investing da’wah project. We would like to give you an image about this project so that you tell us your opinion and the Islamic rulings on this, asking Allah to greaten your reward.

The project is about the following: the office will make a contract with one of the associations or the national factories to make cold juices available free for the pilgrims (visiting the Ka’bah). One carton of juice will cost the office for example 70 (halalah) and then we will offer them for who wants to share in this charity for one riyal, and the difference of this price will be considered support for the office. We will write in the advertisement that the profit of this project will be for the da’wah work of the office.

What is the Islamic ruling on this matter? How should we avoid any prohibited matter?
Praise be to Allah.
    There is nothing wrong with you doing the program mentioned 
    in the question, so long as you write in the advert “Profits raised by this 
    project will go to support the work of the da’wah office”. Thus donors will 
    be aware of the situation and will understand that you are going to make a 
    profit from this program, and that this profit will support the work of the 
    da’wah office. 

    You do not have to tell donors exactly how much the profit 
    that you are going to make will be, because the one who is taking part in 
    this program is doing so with the intention of giving a charitable donation, 
    not with the intention of entering into a business transaction, and it is 
    known that charitable donations are usually based on tolerance and not on 
    competition.  

    We ask Allaah to bless your efforts and benefit others 
    through them. 
And Allaah knows best.