Halacha

הלכה א
עֲשָׂרָה מִינֵי פַּסְלוּת הֵם כָּל מִי שֶׁנִּמְצָא בּוֹ אֶחָד מֵהֶן הֲרֵי הוּא פָּסוּל לְעֵדוּת. וְאֵלּוּ הֵן. הַנָּשִׁים. וְהָעֲבָדִים. וְהַקְּטַנִּים. וְהַשּׁוֹטִים. וְהַחֵרְשִׁים. וְהַסּוּמִים. וְהָרְשָׁעִים. וְהַבְּזוּיִין. וְהַקְּרוֹבִין. וְהַנּוֹגְעִין בְּעֵדוּתָן. הֲרֵי אֵלּוּ עֲשָׂרָה:
כסף משנה
1.
There are ten categories of disqualifications. Any person belonging to one of them is not acceptable as a witness. They are:
a) women;
b) servants;
c) minors;
d) mentally or emotionally unstable individuals;
e) deaf-mutes;
f) the blind;
g) the wicked; h) debased individuals;
i) relatives;
j) people who have a vested interest in the matter; a total of ten.

הלכה ב
נָשִׁים פְּסוּלוֹת לְעֵדוּת מִן הַתּוֹרָה שֶׁנֶּאֱמַר (דברים יז ו) "עַל פִּי שְׁנַיִם עֵדִים" לָשׁוֹן זָכָר וְלֹא לָשׁוֹן נְקֵבָה:
כסף משנה
2.
Women are unacceptable as witnesses according to Scriptural Law, as Deuteronomy 17:6 states: "According to the testimony of two witnesses." The verse uses a male form and not a female form.

הלכה ג
וְכֵן הַטֻּמְטוּם וְהָאַנְדְּרוֹגִינוּס פְּסוּלִין מִפְּנֵי שֶׁהֵן סָפֵק אִשָּׁה. וְכָל מִי שֶׁהוּא סָפֵק כָּשֵׁר סָפֵק פָּסוּל הֲרֵי הוּא פָּסוּל שֶׁאֵין הָעֵד בָּא אֶלָּא לְהוֹצִיא מָמוֹן עַל פִּיו אוֹ לְחַיֵּב עַל פִּיו וְאֵין מוֹצִיאִין מָמוֹן מִסָּפֵק וְאֵין עוֹנְשִׁין מִסָּפֵק דִּין תּוֹרָה:
כסף משנה
3.
A tumtum and an androgynus are also unacceptable, for there is an unresolved doubt whether they are considered as women. Whenever there is an unresolved doubt whether or not a person is acceptable as a witness, he is not accepted. The rationale is that a witness is coming to expropriate money from a defendant based on his testimony or to cause a defendant to be held liable for punishment. And according to Scriptural Law, money may not be expropriated when there is a doubt involved, nor do we inflict punishment when there is a doubt involved.

הלכה ד
הָעֲבָדִים פְּסוּלִין לְעֵדוּת מִן הַתּוֹרָה. שֶׁנֶּאֱמַר (דברים יט יט) "וַעֲשִׂיתֶם לוֹ כַּאֲשֶׁר זָמַם לַעֲשׂוֹת לְאָחִיו" מִכְּלָל שֶׁאָחִיו כָּמוֹהוּ מָה אָחִיו בֶּן בְּרִית אַף הָעֵד בֶּן בְּרִית קַל וָחֹמֶר לְעַכּוּ''ם אִם עֲבָדִים שֶׁהֵן בְּמִקְצָת מִצְוֹת פְּסוּלִין הָעַכּוּ''ם לֹא כָּל שֶׁכֵּן:
כסף משנה
4.
Servants are not acceptable to offer testimony according to Scriptural Law, as can be inferred from Deuteronomy 19:19: "And you shall do unto him as he conspired to do unto his brother." Implied is that his brother is like him. Just as his brother is a member of the covenant; so, too, the witness must be a member of the covenant.
By extension, we can infer that a gentile is certainly not acceptable. If servants who are obligated in certain mitzvot are unacceptable, certainly, this would apply with regard to gentiles.

הלכה ה
מִי שֶׁחֶצְיוֹ עֶבֶד וְחֶצְיוֹ בֶּן חוֹרִין פָּסוּל:
כסף משנה
5.
A person who is half a servant and half a free man is not acceptable as a witness.

הלכה ו
כָּל מִי שֶׁנִּשְׁתַּחְרֵר וַהֲרֵי הוּא מְחֻסָּר גֵּט שִׁחְרוּר. פָּסוּל עַד שֶׁיַּגִּיעַ גֵּט לְיָדוֹ וְיֵעָשֶׂה מִכְּלַל בְּנֵי בְּרִית וְאַחַר כָּךְ יָעִיד:
כסף משנה
6.
Whenever a servant has been freed, but he has not been given his bill of release, he is not acceptable as a witness. Only after the bill of release reaches his hand, he immerses himself in the mikveh, and he becomes a member of the covenant may he give testimony.

הלכה ז
הַקְּטַנִּים פְּסוּלִין לְעֵדוּת מִן הַתּוֹרָה שֶׁנֶּאֱמַר בְּעֵדִים (דברים יט יז) "וְעָמְדוּ שְׁנֵי הָאֲנָשִׁים" אֲנָשִׁים וְלֹא קְטַנִּים. אֲפִלּוּ הָיָה הַקָּטָן נָבוֹן וְחָכָם הֲרֵי הוּא פָּסוּל עַד שֶׁיָּבִיא שְׁתֵּי שְׂעָרוֹת אַחַר שְׁלֹשׁ עֶשְׂרֵה שָׁנָה גְּמוּרוֹת. וְאִם הִגִּיעַ לְעֶשְׂרִים שָׁנָה וְלֹא הֵבִיא שְׁתֵּי שְׂעָרוֹת וְנוֹלַד בּוֹ סִימָן מִסִּימָנֵי סֵרוּס הֲרֵי זֶה סָרִיס וְיָעִיד. וְאִם לֹא נוֹלַד בּוֹ לֹא יָעִיד עַד רֹב שְׁנוֹתָיו כְּמוֹ שֶׁבֵּאַרְנוּ בְּהִלְכוֹת אִישׁוּת:
כסף משנה
7.
Minors are unacceptable as witnesses according to Scriptural Law. This concept is derived as follows: With regard to witnesses, Deuteronomy 19:17 states: "And the two men will stand." Implied is "men," and not minors. Even if the minor was understanding and wise, he is not acceptable until he manifests signs of physical maturity after completing thirteen full years of life.
If he reached the age of 20 without manifesting signs of physical maturity and on the contrary manifests physical signs of a lack of sexual potency, he is classified as a eunuch and may testify. If he does not manifest such signs, he may not testify until he completes the majority of his life, as we explained in Hilchot Ishut.

הלכה ח
קָטָן שֶׁהִגִּיעַ לִכְלַל שְׁנוֹתָיו שֶׁנִּרְאוּ בּוֹ סִימָנֵי בַּגְרוּת מִלְּמַעְלָה אֵינוֹ צָרִיךְ בְּדִיקָה. וְאִם לָאו אֵין מְקַבְּלִין עֵדוּתוֹ עַד שֶׁיִּבָּדֵק. וּבֶן שְׁלֹשׁ עֶשְׂרֵה שָׁנָה וְיוֹם אֶחָד שֶׁהֵבִיא שְׁתֵּי שְׂעָרוֹת וְאֵינוֹ יוֹדֵעַ בְּטִיב מַשָּׂא וּמַתָּן אֵין עֵדוּתוֹ עֵדוּת בְּקַרְקָעוֹת מִפְּנֵי שֶׁאֵינוֹ מְדַקְדֵּק בִּדְבָרִים שֶׁהֲרֵי אֵינוֹ יוֹדֵעַ. אֲבָל בְּעֵדוּת מִטַּלְטְלִין מְקַבְּלִין עֵדוּתוֹ הוֹאִיל וְהוּא גָּדוֹל:
כסף משנה
8.
When a minor passes the age of thirteen and manifest signs of physical maturity in his upper body, he need not be checked to see whether he manifested signs of physical maturity in his lower body. If he does not manifest the upper signs of maturity, we do not accept him as a witness until he is inspected. When a child is thirteen years and one day and manifests signs of physical maturity, but is not very familiar with business dealings, his testimony is not accepted with regard to landed property. The rationale is that he is not precise about such matters because of his unfamiliarity. With regard to movable property, we accept his testimony since he has reached majority.

הלכה ט
הַשּׁוֹטֶה פָּסוּל לְעֵדוּת מִן הַתּוֹרָה לְפִי שֶׁאֵינוֹ בֶּן מִצְוֹת. וְלֹא שׁוֹטֶה שֶׁהוּא מְהַלֵּךְ עָרֹם וּמְשַׁבֵּר כֵּלִים וְזוֹרֵק אֲבָנִים בִּלְבַד. אֶלָּא כָּל מִי שֶׁנִּטְרְפָה דַּעְתּוֹ וְנִמְצֵאת דַּעְתּוֹ מְשֻׁבֶּשֶׁת תָּמִיד בְּדָבָר מִן הַדְּבָרִים אַף עַל פִּי שֶׁהוּא מְדַבֵּר וְשׁוֹאֵל כָּעִנְיָן בִּשְׁאָר דְּבָרִים הֲרֵי זֶה פָּסוּל וּבִכְלַל שׁוֹטִים יֵחָשֵׁב. הַנִּכְפֶּה בְּעֵת כְּפִיָּתוֹ פָּסוּל וּבְעֵת שֶׁהוּא בָּרִיא כָּשֵׁר. וְאֶחָד הַנִּכְפֶּה מִזְּמַן לִזְמַן אוֹ הַנִּכְפֶּה תָּמִיד בְּלֹא עֵת קָבוּעַ. וְהוּא שֶׁלֹּא תִּהְיֶה דַּעְתּוֹ מְשֻׁבֶּשֶׁת תָּמִיד שֶׁהֲרֵי יֵשׁ שָׁם נִכְפִּים שֶׁגַּם בְּעֵת בְּרִיאוּתָם דַּעְתָּם מִטָּרֶפֶת עֲלֵיהֶם. וְצָרִיךְ לְהִתְיַשֵּׁב בְּעֵדוּת הַנִּכְפִּין הַרְבֵּה:
כסף משנה
9.
A person who is mentally or emotionally unstable is not acceptable as a witness according to Scriptural Law, for he is not obligated in the mitzvot. We are not speaking about only an unstable person who goes around naked, destroys utensils, and throws stones. Instead, it applies to anyone whose mind is disturbed and continually confused when it comes to certain matters although he can speak and ask questions to the point regarding other matters. Such a person is considered unacceptable and is placed in the category of unstable people.
An epileptic in the midst of a seizure is unacceptable as a witness. When he is healthy, he is acceptable. This applies both with regard to an epileptic who has seizures only infrequently and one who continuously has seizures without having a fixed time for them, provided his mind is not continuously confused. For there are epileptics whose minds are disturbed even when they are healthy. One must ponder much before accepting testimony from epileptics.

הלכה י
הַפְּתָאִים בְּיוֹתֵר שֶׁאֵין מַכִּירִין דְּבָרִים שֶׁסּוֹתְרִין זֶה אֶת זֶה וְלֹא יָבִינוּ עִנְיְנֵי הַדָּבָר כְּדֶרֶךְ שֶׁמְּבִינִין שְׁאָר עַם הָאָרֶץ. וְכֵן הַמְבֹהָלִים וְהַנֶּחְפָּזִים בְּדַעְתָּם וְהַמִּשְׁתַּגְּעִים בְּיוֹתֵר הֲרֵי אֵלּוּ בִּכְלַל הַשּׁוֹטִים. וְדָבָר זֶה לְפִי (מַה) שֶּׁיִּרְאֶה הַדַּיָּן שֶׁאִי אֶפְשָׁר לְכַוֵּן הַדַּעַת בִּכְתָב:
כסף משנה
10.
People who are very feeble-witted who do not understand that matters contradict each other and are incapable of comprehending a concept as it would be comprehended by people at large are considered among those mentally unstable. This also applies to the people who are continually unsettled, tumultuous, and deranged. This matter is dependent on the judgment of the judge. It is impossible to describe the mental and emotional states of people in a text.

הלכה יא
הַחֵרֵשׁ כְּשׁוֹטֶה שֶׁאֵין דַּעְתּוֹ נְכוֹנָה וְאֵינוֹ בֶּן מִצְוֹת. וְאֶחָד חֵרֵשׁ מְדַבֵּר וְאֵינוֹ שׁוֹמֵעַ אוֹ שׁוֹמֵעַ וְאֵינוֹ מְדַבֵּר. אַף עַל פִּי שֶׁרְאִיָּתוֹ רְאִיָּה מְעֻלָּה וְדַעְתּוֹ נְכוֹנָה צָרִיךְ לְהָעִיד בְּבֵית דִּין בְּפִיו. אוֹ שֶׁיִּהְיֶה רָאוּי לְהָעִיד בְּפִיו. וְיִהְיֶה רָאוּי לִשְׁמֹעַ הַדַּיָּנִים וְהָאִיּוּם שֶׁמְּאַיְּמִין עָלָיו. וְכֵן אִם נִשְׁתַּתֵּק אַף עַל פִּי שֶׁנִּבְדַּק בְּדֶרֶךְ שֶׁבּוֹדְקִין לְעִנְיַן גִּטִּין וְנִמְצֵאת עֵדוּתוֹ מְכֻוֶּנֶת וְהֵעִיד בְּפָנֵינוּ בִּכְתַב יָדוֹ אֵינָהּ עֵדוּת כְּלָל. חוּץ מֵעֵדוּת אִשָּׁה לְפִי שֶׁבְּעִגּוּנָהּ הֵקֵלּוּ:
כסף משנה
11.
A deaf-mute is equivalent to a mentally unstable person, for he is not of sound mind and is therefore not obligated in the observance of the mitzvot. Both a deaf person who can speak and a person who can hear, but is mute is unacceptable to serve as a witness. Even though he sees excellently and his mind is sound, he must deliver testimony orally in court or be fit to deliver testimony orally and must be fit to hear the judges and the warning they administer to him.
Similarly, if a person loses the ability to speak, even though his intellectual faculties have been checked as a husband is checked with regard to a bill of divorce, he testifies in writing, and his testimony is to the point, it is not accepted at all, except with regard to releasing a women from marriage, for leniency was granted so that women will not be forced to live alone.

הלכה יב
הַסּוּמִים אַף עַל פִּי שֶׁמַּכִּירִין הַקּוֹל וְיָדְעוּ הָאֲנָשִׁים הֲרֵי אֵלּוּ פְּסוּלִין מִן הַתּוֹרָה. שֶׁנֶּאֱמַר (ויקרא ה א) "וְהוּא עֵד אוֹ רָאָה" מִי שֶׁהוּא רָאוּי לִרְאוֹת הוּא שֶׁמֵּעִיד. וְהַסּוּמָא בְּאַחַת מֵעֵינָיו כָּשֵׁר לְהָעִיד:
כסף משנה
12.
The blind, although they can recognize the voices of the litigants and know their identities, are not acceptable as witnesses according to Scriptural Law. This is derived from Leviticus 5:1: "And he witnessed or saw," which implies that one who can see may serve as a witness.
A person who is blind in one eye is fit to serve as a witness.

שופטים הלכות עדות פרק ט
Shoftim Edus Chapter 9