What is Imam Malik's ruling on a divorce that occurred between a couple who did not desire it, with this happening repeatedly without witnesses?

Imam Malik holds that an explicit or implicit divorce becomes binding, even if uttered in jest or in a state of anger that does not remove one's sanity. Thus, if a husband pronounces the word 'divorce' or intends divorce with another utterance, the divorce takes effect and becomes binding, based on the hadith: "There are three matters which, whether done seriously or in jest, are considered serious: marriage, divorce, and revocation [of divorce]." The absence of witnesses does not affect the validity of the divorce, as witnessing is merely recommended. So, whoever divorces his wife, she is divorced from him, and if the divorce reaches three pronouncements in a single session, she becomes irrevocably separated from him and is not lawful for him until she marries another husband.