On the Mishnah (Avos 5:22) which states: “Hafoch bah vahafoch bah d’cholah vah”, “Delve into [the Torah] and delve into it again, because everything is contained in it”. Rav Chaim Volozhiner writes, in Ruach Chaim, that every time a person studies Torah, even if a person thinks the halachos he is studying are inapplicable to him, they are not at all irrelevant, for we still learn one law from another. For instance, he says, from the halachos of succah we can derive a way to release an agunah (a “chained” woman, i.e., a woman whose husband’s whereabouts are unknown or who refuses to give her a get).
Many talmiday chachomim have wondered to what halachah in Hilchos Succah Rav Chaim Volozhiner was referring. How can an agunah be released using a law of succah?
When this question was posed to Rav Chaim Kanievsky, he cited the following Gemara in Bava Basra (162b): Chizkiyah said: If the sofar [scribe] filled the two-line space between the text and signatures in a document with the signatures of relatives, the document is valid. And do not wonder how it can be that a blank space renders a document invalid, while if that same space is filled with ineligible signatures the document is valid. For we find a similar situation elsewhere: Air space three tefochim wide in the roof of a succah invalidates the succah, while an unsuitable covering invalidates only if it is four tefochim wide.
In other words: Just as open space in a succah is worse than an unsuitable covering, blank space in a document is worse than ineligible signatures.
This halachah in Hilchos Succah is instructive for the writing of a get document, which is a means of freeing an agunah.
