Talmud for Parah 2:5
הָיוּ בָהּ שְׁתֵּי שְׂעָרוֹת שְׁחוֹרוֹת אוֹ לְבָנוֹת בְּתוֹךְ גֻּמָּא אַחַת, פְּסוּלָה. רַבִּי יְהוּדָה אוֹמֵר, אֲפִלּוּ בְתוֹךְ כּוֹס אֶחָד. הָיוּ בְתוֹךְ שְׁנֵי כוֹסוֹת וְהֵן מוֹכִיחוֹת זוֹ אֶת זוֹ, פְּסוּלָה. רַבִּי עֲקִיבָא אוֹמֵר, אֲפִלּוּ אַרְבַּע, אֲפִלּוּ חָמֵשׁ, וְהֵן מְפֻזָּרוֹת, יִתְלֹשׁ. רַבִּי אֱלִיעֶזֶר אוֹמֵר, אֲפִלּוּ חֲמִשִּׁים. רַבִּי יְהוֹשֻׁעַ בֶּן בְּתֵירָא אוֹמֵר, אֲפִלּוּ אַחַת בְּרֹאשָׁהּ וְאַחַת בִּזְנָבָהּ, פְּסוּלָה. הָיוּ בָהּ שְׁתֵּי שְׂעָרוֹת, עִקָּרָן מַשְׁחִיר וְרֹאשָׁן מַאְדִּים, עִקָּרָן מַאְדִּים וְרֹאשָׁן מַשְׁחִיר, הַכֹּל הוֹלֵךְ אַחַר הַנִּרְאֶה, דִּבְרֵי רַבִּי מֵאִיר. וַחֲכָמִים אוֹמְרִים, אַחַר הָעִקָּר:
[If] it had two black or white hairs from one pore, it is invalid. Rabbi Yehuda says: even from one cup [a bump of flesh from which several hairs grow]. If they [the two hairs] are from two cups, and they prove one another [giving indication that they grew in tandem], it is invalid. Rabbi Akiva says: Even four or even five scattered [hairs], they should be plucked [and the cow is valid]." Rabbi Eliezer says: Even fifty. Rabbi Yehoshua ben Beteira says: Even one at its head and one at its tail invalidate it. [If] it had two hairs whose roots are black and tips are red, [or] whose roots are red and tips are black, everything follows after the appearance [i.e. the tips], these are the words of Rabbi Meir; and the Sages say: after the root.