Maharsha Sanhedrin 98b
משיח נקרא ע"ש של הקב"ה שנאמר זה שמו אשר יקראו ה' צדקנו וחנינה שמו וגם בשם זה יש בו שם ד'בחילוף נ' אחד בה' באי"ק בכ"ר ויהיה באותיותיו חן ה' ומנחם בן חזקיה שמו שנאמר כי רחק ממני מנחם גו' ירמיה אמרו בשעת חורבן שאז נולד משיח ונתרחק מבני אדם לג"ע כדאיתא במדרשים ובן חזקיה לאו מקרא משתמע אלא קבלה בידם הוא ורבנן דאמרי חיורא
Eicha Rabba 1:51
The following story supports what Rabbi Yudan said in the name of Rabbi Aibu: A man was plowing his field when his ox lowed. An Arab passed by and asked "What are you?" And he answered "I am a Jew." The Arab man said to him, "Untie your ox and unharness your plough" [as a sign of mourning]. "Why?" he asked. "Because the Temple of the Jews is destroyed," said the Arab. "From where do you know that?" asked the Jew. "I know it because your ox lowed," answered the Arab. While they were talked the ox lowed again. "Harness your ox and tie up the plough again, because the deliverer (moshiach) of the Jews has been born" said the Arab. "What is his name?" asked the Jew. "Menachem (comforter)," answered the Arab.
....Rabbi Abun asks: Why do I need to be taught of this from the Arab man? I have the two pesukim 'And the Lebanon shall fall my a mighty one' which is closely followed by [and therefor connected to] 'And there shall come forth a shoot out of the stock of Jesse, and a twig shall grow forth from his roots.'
(Midrash Rabbah on Lamentations 4:15).
Should not the verse have said "A weeping to Asaf," "A wail to Asaf," "A lament to Asaf"? Why does it say "A song to Asaf"?
But this is analogous to a king who built a nuptial home for his son, and had it beautifully plastered, inlaid and decorated. Then this son strayed off to an evil life. So the king came to the nuptial canopy, tore down the tapestries and broke the rails. Upon which the prince's tutor took a flute and began to play. Those who saw him asked: "The king is overturning the nuptial canopy of his son, and you sit and sing?" Said he to them: "I am singing because the king overturned his son's nuptial canopy, and did not vent his wrath upon his son."
So, too, was asked of Asaf: "G‑d destroyed the Temple and Sanctuary, and you sit and sing?" Replied he: "I am singing because G‑d vented His wrath upon wood and stone, and did not vent his wrath upon Israel"
The Shulchan Aruch (559:4) writes: We do not recite Tachanun on Tisha B'Av and we do not fall on our faces because it is considered a festival. Shulchan Aruch 559:4
One does not recite Kiddush Levana prior to Tisha B’av. It is rather to be recited on Motzei Tisha B’av. Custom of Arizal
The reason: The reason for saying Kiddush Levana specifically on Motzei Tisha B’av is because that is the time Moshiach was born and the renewal of the moon represents that the Jewish people will return to a renewed state. [Kaf Hachaim Kaf Hachaim 551:117; &426:29 in name of Rav Chaim Vital]
Sefer Kol Bo 62 It is a long standing custom that women wash their hair on Tisha B’Av beginning with the earliest time to recite Mincha and our first elders looked upon the practice favorably. They based their approval on what we learned in Aggadita that the Moshiach was born on Tisha B’Av. That means that just as we spent time on Tisha B’Av mourning the destruction of the Beis Hamikdash and sitting on the floor so too we must spend time looking forward to the coming of the Moshiach so that we do not abandon all hope for his coming. This act was necessary only for women who are weak but we men are believers and confident that the prophecies of comfort and redemption will be fulfilled but women who have not studied those prophecies need to undertake a concrete act to strengthen their beliefs.
It is also explained in the Meiri (Taanis 30A )that in Narbona it was the custom among the women to wash their heads from Mincha time forward on Tisha B’Av and we heard that the elders and Rabbinic leaders directed them to do so based on a Midrash that relates that the Moshiach was born on Tisha B’Av and that following the custom demonstrated accepting comfort and faith in the coming of the redemption and the Meiri himself expressed no objection to the practice even though there may be halachic problems with it.
Birkei Yosef Aruch Chaim
It is the practice among many to recite verses of comfort on Tisha B’Av during Mincha. The Rabbi Shayarei Knesses Ha’Gedola in the name of Rabbi Tzeidah L’Derech questioned the practice based on the rule that we are not to learn Torah during any part of Tisha B’Av. He further wrote that since the practice is not referred to in the Tur or the Beis Yossef he did not recite those verses but did not stop others from doing so. The Rav Yad Aharon found support for the practice from the words of the Hegos Maiymon that were quoted by the Beis Yossef. I will add to his words that since in the days of Rav Yossef Karo there were already printed Siddurim and Machzorim that included the practice, if he objected to it, he would have said so. His silence supports the view that he approved of the practice.
Ashkenazim Recite After Reciting Kinos verses of comfort both In the evening and morning
Show compassion to Tzion as You said. Re-reestablish Tzion as You declared. Hasten the rescue and speed along the redemption. Return to Yerushalayim with abundant compassion.
As it is written among the words of the prophets: Therefore, so says G-d, I will return to Yerushalayim with abundant compassion, My home will be rebuilt there, that is the declaration of G-d, lord of Hosts and a measuring string will be strung across Yerushalayim.
And in another work of prophecy it is said: So said G-d Lord of Hosts, My cities shall again overflow with good and G-d will once again comfort Tzion and G-d will choose Yerushalayim as His place of residence.
And it is written: That G-d will comfort Tzion; comforts its ruins and will turn its deserts into Eden and its desolate areas into the gardens of G-d, the sound of joy and happiness will be found there; thanksgiving and the sound of song.
Birkei Yosef Aruch Chaim
I further saw in the book of Kavanos of the AR”I (p. 89, side three) who referred to the practice and supported it based on what our Sages said that when the Jewish people saw that on Tisha B’Av in the evening, the Beis Hamikdash was set on fire, they recited a chapter of Tehillim, acknowledging that G-d had cast His anger on the wood and stone that comprised the Beis Hamikdash and not on them, and they were happy, because if not, the Jewish People would have ceased to exist , so they were comforted, therefore we should recite verses of comfort as well. Rabbi Chayim Vital wrote there that he heard another reason from his teacher: that at Mincha time on Tisha B’Abv the Moshiach was born who is known as Menachem (comforter) . I further found written that for this reason, or Sages did not interfere with the practice among women who with all their strength clean the house and arrange the beds, and other chores around the house which is an ancient custom among the Jewish women of Italy and because their intelligence is below average and their faith is weak, undertook these activities to strengthen their faith that the redemption will come and will not abandon all hope.
The customary given to the Shabbos before Tisha B’Av is Shabbos Cha’Zone because of the first word of the Haftorah read that day (Chazone Yishayahu) and already many who are experts on Jewish customs expressed surprise and asked: We understand why the Shabbos after Tisha B’Av is called Shabbos Nachamu, because of the words of comfort contained therein but why is the Shabbos before Tisha B’Av known as Shabbos Chazone (prophecy)?
So they answered that it is based on the verse in Zechariya letting us know that one day the fasts during the year will become days of celebration. Therefore it is named
Shabbos Cha’Zone-a prophecy about Tisha B’Av, a day of mourning, becoming a day of celebration. Those who study acronyms said the word Chazone is an acronym: i.e. half of it is a day of anger and half the day is a day to take comfort; or partly a day of anger and partly a day of comfort because during the week that follows reciting the Chazone Haftorah, Tisha B’Av will be commemorated after which we will begin to read Haftorah that provide us comfort.
North African Jewish Customs
The Candle Of Moshiach -On Tisha B’Av in the afternoon, they put the house into a festive atmosphere; they decorate the house with rugs and flowers. They sprinkle around the house gold dust. Women wash their hair and dress in festive clothes-in honor of the Moshiach who was born on Tisha B’Av. At the same time, many enter into synagogues to grill what is known as the offering of Tisha B’Av, a bull to act as a sin offering that is purchased with communal funds and its meat is then divided among the poor. And in honor of the birth of the Moshiach, they light a candle in synagogue for the third time, the same candle they lit at the onset of the fast but this time for a festive reason out of expectation that the ultimate redemption will take place in fulfillment of the words of the prophet of comfort: To appoint to those who mourn in Zion, to give to them a garland instead of ashes, the oil of joy instead of mourning, the garment of praise instead of the spirit of heaviness; that they might be called trees of righteousness, the planting of the Lord, that he might be glorified. (Yeshayahu 61, 3).
Midrash tanchumah Buber Shemos
G-d said to the Jewish People: my children, in this world you are responsible to provide light in the Beis Hamikdash and for that purpose you light candles within it but in the future, in the merit of the candles that you would light, I will redeem you through the acts of the Moshiach who is compared to a candle as it is written (Tehillim 132, 17): There I will make the horn of David to sprout; I have prepared a lamp for my anointed.