Who are "Meshichai"?
Rashi: My great ones. Every Meshichah is an expression of authority and grandeur.
Radak: They are nobles. They were honored among kings, as if they were anointed kings. Bnei Ches told Avraham "Nesi Elokim Atah b'Sochenu" (Bereishis 23:6), and Avimelech went after Yitzchak to make Shalom with him.
Gra (Divrei ha'Yamim I, 16:20): The women - "Lo Nesaticha Lingo'a 1 Eleha" (Bereishis 20:6).
I.e. Hashem did not let Avimelech touch Sarah. (PF)
How did Hashem tell them not to touch "Meshichai"?
Radak: He warned Avimelech and Lavan in dreams, and sent plagues against Pharaoh and Avimelech. 'Rashi' (Divrei ha'Yamim I, 16:22) - also, when Kena'anim wanted to kill Yakov because [his sons] wiped out Shechem, [they did not, for] "fear of Elokim" (Bereishis 35:5) was on them.
Malbim: All this is "Davar Tzivah l'Elef Dor" (verse 8).
Who are "Nevi'ai"?
Radak: The Avos; they were Nevi'im. Hashem spoke to them in prophecy and in dreams. It says about Avraham "Hashev Eshes ha'Ish Ki Navi Hu" (Bereishis 20:7).
