Should you refuse to lend money to a suitor from a deposit designated for buying a house, knowing that you swore not to touch it, and that he is a man of religion and good character, and he insists on asking you for the money?

If the deposit is in a usurious bank, the money must be withdrawn from it. A woman's conversation with a non-mahram man is not permissible except for a valid need, and this includes conversation for the purpose of marriage and during the engagement period before the contract. Refusing to lend to the man is permissible. If you wish to lend to him, it should be through your mahrams after consulting them and ascertaining his religiosity and trustworthiness. It is better to write this down and have witnesses to it. If the loan is from the deposit, then you owe expiation for an oath.