As-Salamu alaykum,
I work in a project for purchasing clothes and selling them in cash or monthly installments. It is a small project with a small capital. Some customers contact me, asking for clothes with certain sizes, which I do not have; they want me to buy those for them, or they ask me to buy them a fridge although I deal in clothes. Is it permissible for me to sell them the commodity in installments, or must the commodity be in my possession so that I can sell it to him? Because the project is small, I cannot buy many commodities and wait until someone buys them. What should I do if no one buys them?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

It is permissible to buy clothes, sell them, and get paid in installments. It is also permissible that you buy what the customer asks of you and then to sell it to him and get paid in installments, for a higher price than the one you paid the commodity for. It is conditioned that you do not conclude a contract of sale with the customer unless you bought the commodity and have full possession of it. This being said, it is not permissible that you conclude a contract of sale with him or give him a binding promise that you will buy him the commodity, because you will be selling what you do not possess. It is narrated on the authority of Hakeem ibn Hizaam that he said,

I went to the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, and said, "A man would come and ask me to sell him what I do not have. Should I buy from the market and then sell the thing to him?" The Prophet, sallallaahu ‘alayhi wa sallam, said, "Do not sell what you do not have." [At-Tirmithi and Ibn Maajah] [Al-Albaani: Saheeh]