What is the difference between this Pasuk and the following one? Why is the sinner Chayav bi'Yedei Shamayim in this Pasuk and Misah bi'Yedei Adam in the following one?
Rashi: This Pasuk speaks where there are no witnesses, in which case the blasphemer is Chayav Kares; The following Pasuk speaks where there are witnesses, in which case he is Chayav Misah at the hand of Beis-Din, provided he specifies Hashem's Name before blaspheming it.
Rashbam and Targum Yonasan: This Pasuk is speaking where someone blasphemes one of the Names of Hashem without specifying the unique Name of Havayah, in which case he is punishable by Hashem, whereas if He first mentions the Name of Havayah, he is Chayav Misah bi'Yedei Adam. 1
Seforno: The current Pasuk refers to the Lav of cursing a Dayan, who is punishable at the Hand of Hashem depending upon the status of the curser and the cursed, especially if the former did not curse with the Name of Hashem or he merely denigrated the Dayan; whereas the following Pasuk is speaking about somebody who blasphemes Hashem. 2
Targum Onkelos: This Pasuk is speaking about someone who curses Hashem without mentioning His Name is Chayav at the Hand of Hashem; whereas the following Pasuk sentences someone who specifies Hashem's Holy Name to Misah at the hand of Beis-Din.
Da'as Zekenim, Hadar Zekenim: This verse discusses cursing a judge or Nasi; he bears his sin through lashes - "Elokim Lo Sekalel." The next Pasuk discusses one who curses Hashem. He streteched out his hand against the Source, so he is killed.
Riva: Here, he cursed 'Elohim 3 '. Perhaps he intended for (Ibn Ezra - angels or) judges, who are called 'Elohim.' Therefore, we cannot kill him.
Riva: Someone from one of the nations who curses Elokav will be punished - monetarily 4 , but if he curses Hashem's name, he will die.
See also Torah Temimah, citing Sanhedrin, 56a.
Normally, one says 'Elohim' to refer to judges, and Elokim for Hashem, 'Elokim'. Here is different, for one who curses Hashem is not concerned for saying His name l'Vatalah! To be Chayav Misah, one must accept warning, and say 'I do so, knowing that I will be killed for it.' If he did so, surely he intended to curse Hashem! Perhaps if he says afterwards 'I retracted, and decided to curse only the judge', we cannot kill him, lest he truly did. Alternatively, we discuss a Chacham, according to the opinion that a Chacham need not be warned, (PF)
I do not know his source for this. (PF)
Why does the Torah repeat the word "Ish"?
Torah Temimah (citing Sanhedrin, 56a): To teach that Nochrim are also included in the prohibition of blaspheming Hashem.
Why does it say "v'El Bnei Yisrael Tedaber
Moshav Zekenim (14): One might have thought that it was a Hora'as Sha'ah to stone him naked. This teaches that it is a Mitzvah for all generations.