Reference for Taanit 4:7
שַׁבָּת שֶׁחָל תִּשְׁעָה בְאָב לִהְיוֹת בְּתוֹכָהּ, אָסוּר מִלְּסַפֵּר וּמִלְּכַבֵּס, וּבַחֲמִישִׁי מֻתָּרִין מִפְּנֵי כְבוֹד הַשַּׁבָּת. עֶרֶב תִּשְׁעָה בְאָב לֹא יֹאכַל אָדָם שְׁנֵי תַבְשִׁילִין, לֹא יֹאכַל בָּשָׂר וְלֹא יִשְׁתֶּה יָיִן. רַבָּן שִׁמְעוֹן בֶּן גַּמְלִיאֵל אוֹמֵר, יְשַׁנֶּה. רַבִּי יְהוּדָה מְחַיֵּב בִּכְפִיַּת הַמִּטָּה, וְלֹא הוֹדוּ לוֹ חֲכָמִים:
During the week in which the ninth of Av happens, it is prohibited to a person to shave himself, or to wash [his clothes], but on Thursday it is allowed in honour of the Sabbath. On the day before the ninth of Ab, a person may not partake of two [different kinds] of cookeries [or dishes], eat meat, or drink wine thereon. Rabbon Simeon ben Gamaliel says "[It is sufficient to] alter [from one's customary mode of living]." Rabbi Yehudah considers it obligatory to turn over the bed places, but the sages do not agree in this.