certainly joseph brought you manifest proofs earlier but you continued to remain in doubt concerning what he had brought you. when he died you said allah will never send any apostle after him. that is how allah leads astray those who are unrestrained and skeptical.
ولقد جاءكم يوسف من قبل بالبينات فما زلتم في شك مما جاءكم به حتى إذا هلك قلتم لن يبعث الله من بعده رسولا كذلك يضل الله من هو مسرف مرتاب