Sheikh Ahmad al-Khalîl, professor at al-Imâm University, Qasîm Branch
If a man divorces his wife while in a state such as drunkenness or anger that compromises his mental faculties, then the validity of the divorce depends on the degree to which his mental faculties have been compromised.
If a man divorces his wife while he is so drunk that he does not know what he is doing, then the divorce will not have occurred, and the marriage will remain as it was.
Likewise, if he divorces her under the stress of anger, we have to consider the degree of his anger. If the anger is uncontrollable and reaches a point where he does not know what he is saying, then again the divorce will not have occurred.
However, if he divorces her under a normal state of anger, then it will be regarded as a single pronouncement of divorce, even if he makes two or three pronouncements, because three pronouncements made together count as one.
Unless it is the third seperate occasion wherein he has divorced his wife, he may resume his marriage as usual by saying to his wife: “I want you to return back to me.” It is better for him to have witnesses when he does this.
Source: Islam Today