This is Hanukkah/ eight day of Hanukka
The eighth day of the Feast of Dedication (the first source is in Deuteronomy 7:11: "This is the dedication of the altar on the day he anointed it from the leaders of Israel").
("You have found this dedication, which we are making in memory of the dedication of the house of Hashmonaim, because they waged war and were victorious over the sons of Yavan, and we are now burning, and so at the hour when the dedication of the tabernacle was completed, they made a dedication, as it is written (in Midrash 7): This is the dedication of the altar" - Pesikta Rabati (Ish Shalom), Pisaka 6, and all the work was paid to them)
Translation
Expression (Hebrew)
זֹאת חֲנֻוכָּה
Definition (Hebrew)
הַיּוֹם הַשְּׁמִינִי שֶׁל חַג הַחֲנֻכָּה (הַמָּקוֹר הָרִאשׁוֹנִי בִּבְמִדְבַּר ז פֵּד:"זֹאת חֲנֻכַּת הַמִּזְבֵּחַ בְּיוֹם הִמָּשַׁח אֹתוֹ מֵאֵת נְשִׂיאֵי יִשְׂרָאֵל").
("אַתְּ מוֹצָא זֹאת הַחֲנֻכָּה שֶׁאָנוּ עוֹשִׂים זֵכֶר לַחֲנֻכַּת בֵּית חַשְׁמוֹנַאי עַל שֶׁעָשׂוּ מִלְחָמָה וְנִצְּחוּ לִבְנֵי יָוָן וְאָנוּ עַכְשָׁו מַדְלִיקִין, וְכֵן בְּשָׁעָה שֶׁנִּגְמְרָה מְלֶאכֶת הַמִּשְׁכָּן עָשׂוּ חֲנֻכָּה כְּמוֹ שֶׁכָּתַב (בַּמִּדְבָּר ז') זֹאת חֲנֻכַּת הַמִּזְבֵּחַ"-פְּסִיקְתָּא רַבָּתִי (אִישׁ שָׁלוֹם) פִּיסְקָא ו, וּתְשַׁלֵּם כָּל הַמְּלָאכָה)