Can I sell an item which I do not own, but will definitely be able to give it to the customer after buying it?

Answer

It is not permissible to sell something which one does not own. First acquire the item, then sell it.

Q Is it permissible for the Masjid committee to use Masjid waqf money for entertainment purposes to buy food and accessories to celebrate Moloodun Nabie etc. and what is the criteria how should Masjid funds be utilize.

A. It is haraam to use Musjid funds for any purpose other than for the expenses of the Musjid. Leave alone the haraam entertainment you have mentioned, it is not permissible to use the funds of the Musjid to buy food for even genuinely poor Muslims. The funds of the Musjid have to be compulsorily used for only the expenses of the Musjid.

The trustees who have stolen the Musjid's funds for moulood functions are scoundrels who have to repay the embezzled amount.