Reference for Megillah 2:4
הַכֹּל כְּשֵׁרִין לִקְרוֹת אֶת הַמְּגִלָּה, חוּץ מֵחֵרֵשׁ, שׁוֹטֶה, וְקָטָן. רַבִּי יְהוּדָה מַכְשִׁיר בְּקָטָן. אֵין קוֹרִין אֶת הַמְּגִלָּה, וְלֹא מָלִין, וְלֹא טוֹבְלִין, וְלֹא מַזִּין, וְכֵן שׁוֹמֶרֶת יוֹם כְּנֶגֶד יוֹם לֹא תִטְבֹּל, עַד שֶׁתָּנֵץ הַחַמָּה. וְכֻלָּן שֶׁעָשׂוּ מִשֶּׁעָלָה עַמּוּד הַשַּׁחַר, כָּשֵׁר:
All [including women] are fit to read the Megillah, except a deaf-mute [(This Mishnah is in accordance with R. Yossi, who says that if one reads and does not "make it heard" to his ears, he has not fulfilled his obligation)], an imbecile, and a minor. R. Yehudah rules it to be fit with a minor. [The halachah is not in accordance with R. Yehudah.] The Megillah is not read, circumcision is not performed, (ritual) immersion is not performed, sprinkling is not performed, and also a woman who observes "day against day" does not immerse until sunrise. And all of them, if they did so at dawn, it is kasher. [("The Megillah is not read":) For one must read the Megillah at night and repeat it in the daytime. And the reading of the daytime is only after sunrise, viz. (Esther 9:28): "And these days are commemorated and celebrated." ("circumcision is not performed":), viz. (Leviticus 12:3): "And on the eighth day he shall circumcise." ("immersion and sprinkling are not performed":) it being written in respect to sprinkling (Numbers 19:19): "And the clean one shall sprinkle on the unclean one on the third day and on the seventh day," and immersion is likened to sprinkling. It is only when he immerses on the seventh day that he must immerse only in the daytime, and we do not say that he may immerse when it gets dark on the night of the seventh, even though the night is the beginning of the day. But after the seventh day has passed, it is permitted to immerse at night. ("a woman who observes 'day against day'":) during the eleven days between one niddah state and the next. If she sees blood on one of those days, she observes the next day (in cleanliness) and immerses that day itself at sunrise. ("if they did so at dawn, it is kasher:") For when the day dawns, it is called "day," viz. (Nechemiah 4:15): "And we did the work … from the dawn until the stars appeared," followed by (Ibid. 16): "…and the night for us was guarding, and the day, work." They said "until sunrise" only to insure that it was not night, for not all are expert in discriminating dawn.]