כָּל־מַ֨כֵּה־נֶ֔פֶשׁ לְפִ֣י עֵדִ֔ים יִרְצַ֖ח אֶת־הָרֹצֵ֑חַ וְעֵ֣ד אֶחָ֔ד לֹא־יַעֲנֶ֥ה בְנֶ֖פֶשׁ לָמֽוּת׃
Setiap orang yang menewaskan seseorang, pembunuh itu harus dihukum mati berdasarkan keterangan para saksi; tetapi satu orang saksi saja tidak boleh memberi kesaksian terhadap seseorang sehingga ia dihukum mati.
Yalkut Shimoni
Why is it stated "כל מכה נפש לפי עדים" (every strike that takes a life requires witnesses)? Because it is written, "And the avenger of blood shall slay the murderer" (Numbers 35:19). I might think that the avenger can kill the murderer on his own, without witnesses. Therefore, it is stated "כל מכה נפש לפי עדים" (every strike that takes a life requires witnesses) to teach that the murderer is not put to death except through witnesses. These are the words of Rabbi Yehoshua. Rabbi Yonatan says, "Why is it stated 'כל מכה נפש לפי עדים' (every strike that takes a life requires witnesses)? Because it is written, 'But the murderer shall not die' (Numbers 35:12). I might think that the murderer is put to death by the court without witnesses. Therefore, it is stated 'כל מכה נפש לפי עדים' (every strike that takes a life requires witnesses) to teach that the murderer is not put to death except through witnesses and by the court."
Yalkut Shimoni
One witness may not respond, whether in favor or against, according to the opinion of Rabbi Yosei bar Yehuda. He may respond in favor but not against. What is the reason for Rabbi Yosei bar Yehuda's opinion? It is derived from the fact that one witness may not respond in a capital case, as he does not respond to establish guilt but may respond in favor. The Rabbis disagree because it appears as if he is interfering with his testimony. And what do the Rabbis derive from the phrase "למות" (to death)? They apply it to include one of the disciples, as it is taught: One of the witnesses says, "I have something to teach regarding him in favor." How do we know that his words are not heard? The verse states, "ועד אחד לא יענה" (one witness may not respond). How do we know that this includes one of the disciples who says, "I have something to teach regarding him in favor [or against]"? How do we know that his words are not heard? The verse states, "אחד לא יענה" (one may not respond). One witness may not respond in a capital case, but may respond in an oath case. The phrase "ועד אחד" (one witness) refers to a person who built his father's house. Wherever it says "עד" (witness), it includes two witnesses until the verse explicitly singles out one witness. "In all your settlements" includes both in the land and outside the land. One might think that even cities of refuge should follow the same rules in both the land and outside the land, therefore it is stated "בכל מושבותיכם" (in all your settlements) to teach that the courts operate in the land and outside the land, but cities of refuge are only applicable in the land.