What is "va'Yshano Es Ta'amo"?
Rashi: He changed his words [Metzudas Tziyon - from being words of Chachmah].
Radak: It is [counsel], like "mi'Ta'am ha'Melech" (Yonah 3:7) and "Baruch Ta'amech" (25:33). 1 He changed it "b'Einehem" - this is like l'Einehem (in front of them).
Yosef Tehilos: Refer to 21:11:2:4.
Malbim: It is his reason [for coming]. Initially he said that he fled Sha'ul. Now he changed, and gave another reason.
Radak: The Vov at the end of va'Yshano is a pronoun in place of Ta'amo. Even though the verse explicitly says Ta'amo, we find like this -"va'Tir'ehu Es ha'Yeled" (Shemos 2:6).
Who made this change in David?
Shochar Tov (34:1): David asked Hashem to put lunacy upon him. 1
All the Meforshim explain like the simple meaning, that David feigned lunacy. (PF)
Shochar Tov: Earlier, David had said "You did all Your deeds with Chachmah" (Tehilim 104:24) - except for all lunacy. Hashem said, do you complain about lunacy? You will need it! Refer also to 24:3:2:1 and the notes there.
What is the meaning of "va'Yis'holel"?
Rashi: He became a lunatic. Mahari Kara - this is like "Holelus v'Sichlus" (Koheles 2;12).
What is the meaning of "b'Yadam"?
Rashi: It is in front of them, i.e. while he was amidst their hands; they surrounded him and stared at him.
What is the meaning of "va'Ysav"?
Rashi: He wrote. 1
Radak, Targum Yonasan: It can be that he merely scratched lines. Also this is called 'Sav'.
Shochar Tov (34:1): He wrote 'Achish Melech Gas owes me 1,000,000, and his wife owes me 500,000.'
What is "Riro"?
Rashi: It is his saliva. Anything that drips is called Rir. The same applies to "b'Rir Chalamos 1 " (Iyov 6:6) and "Rar Besaro" (Vayikra 15:3).
Why did David act like a lunatic?
Radak #1: He wanted them to think that he is not David.
Radak #2: They will not be concerned for him, and will expel him from the king's palace, and he will leave.