Romans 7:2-3

For example, by law a married woman is bound to her husband as long as he is alive, but if her husband dies, she is released from the law that binds her to him. So then, if she has sexual relations with another man while her husband is still alive, she is called an adulteress. But if her husband dies, she is released from that law and is not an adulteress if she marries another man.