Is it permissible to buy religious books and tapes for distribution as Da‘wah gifts during Ramadan with money earned from bank interest, knowing that the money will not be used to buy anything for the questioner or his wife?

Whoever deposited their money in usurious banks out of necessity, ignorance, or heedlessness, and generated interest from it, should spend it on the welfare of Muslims. There is no objection to buying useful books and distributing them to students of knowledge, as a means of getting rid of it, not as charity.