Chapter 123:4&5
Erev Tish'ah B'av
4. In a year when Erev Tish'ah B'av falls on a Monday, a person who [has
taken a vow to] fast [every] Monday and Thursday, should ask a [Rabbi] to
annul his vow (1). A person who has a "yahrzeit" (2) on Erev Tish'ah B'av,
[should do as follows]: In the first year, he should specify that he is
fasting only until midday (that is, halachic "chatzot") [so as to establish
this as his custom]. He should pray Minchah Gedolah, that is [he should
pray the afternoon service] one half hour after midday. He should then eat
a normal meal and, shortly before nightfall, he should eat the se'udah
hamafsekes (final meal before the fast) (3).
5. Everything that is forbidden on Tish'ah B'av itself is also forbidden
between sunset and the appearance of the stars (4). Therefore, one must
remove one's shoes before sunset (5).
FOOTNOTES:
(1) So as to avoid having to fast two days consecutively.
(2) A "yahrzeit" is the anniversary of the death of a close relative. Many
fast on a "yahrzeit."
(3) See HY 123:3
(4) We don't know the precise moment after sunset that it is considered
"nightime" (and thus, the beginning of the next day in the Hebrew
calendar). Once three stars appear, it is definitely considered "night."
The period between sunset and the appearance of three stars is called "Bein
Hashemashos" and due to the doubt involved, we are stringent and view it as
"night" regarding certain laws.
(5) We will see in the next chapter that leather shoes are prohibited on
Tish'ah B'av.