The Machtzis Hashekel (O.Ch.417) quotes the Hagahos Mordechai
in the name of the Tosefta, that there is no Rosh Chodesh Bentching
for the month of Av.
Many Poskim argue and hold that we do Bentch on Shabbos,
Rosh Chodesh Av. The Minhag is to bentch Chodesh Menachem Av,
even though the month is Called Av (no Menachem). We say it so
that we should be zoche to have the Geulah etc. (Aruch Hashulchan E.H. 126)
There are Sheilos if with the word Menachem in a Get causes problems.
They once asked from The Tchebiner Rav zt”l how to date letters & documents written in the month of Av.
He told them the answer can be found in the Teshuvos Chasam Sofer, Orach Chaim.
They came back to the Tchebiner Rav and told him they searched the
whole Sefer and couldn’t find any such discussion.
He told them , “when learning a Teshuvas Chasam Sofer, it is not enough
to learn the text, but one needs to learn the date as well.
If you check Teshuvos # 32, 33, 35, 37, The ones written before Tisha B’av
the Chasam Sofer dates it as Av. The ones written after Tisha B’av he dates them
Menachem or Menachem Av.
I leafed through the seven volumes of Shu”t Ch. S. (1246 Teshuvos)
and found, there are aproximately 150 Teshuvous written by the Chasam Sofer
in the month of Av. All of them follow the rule of the TchebinerRav zt”l,
The ones dated Before 9th Av are dated as Av. The ones after 9th Av are dated as
However there are two days, the 13th and 15th of Av where the Ch. S. dates them
Av, even though they are after 9th Av.
It is possible the 15th of Av being it is mentioned in the Mishna (end m. Ta’anis)
as Chamisha Asar B’av, The Ch. S. didn’t want to change from the Loshon of the Mishna*.
On the 13th of Av the only explanation I can think of, being it is the Yahrzeit
of his first Rebbetzin שרל.
15th of Av 13th of Av
O.Ch. 60 O.Ch. 115
Y.D. 129 O.Ch. 158
E.H. 2: 72 Y.D. 43
Chelek 6 41
Chelek 7 18
*There is one Teshuva (E.H. 2 : 125) on the 15th he dated as Menachem.