Is it permissible for a wife to testify on behalf of her husband in a case concerning a tenant's failure to pay rent, given that she is aware of the details but was not present at the time the arrears were demanded?

It is not permissible for the tenant to delay payment of the rent. The landlord is permitted to demand his right and take the matter to court. His wife may testify to what she heard, specifying the source of her hearing. If the lease contract is monthly or for a fixed term, the landlord may increase the rent upon the expiration of the term and renewal of the contract. However, during the contract term, the tenant cannot be compelled to accept an increase unless he consents.