How did Hashem tell David about this day?
Radak: Shmuel, Gad or Nasan told him that Hashem would give David's enemies in his hands, and he would succeed in his kingship. David's men said that this refers to Sha'ul, the head of his enemies. David held that it need not refer to Sha'ul.
Malbim: A Navi anointed David. Two kings cannot rule together. Sha'ul pursues David; surely he will fall to David, for Hashem promised kingship to him. Surely Hashem caused that he fall to David - it is as if He said to give David's enemy in his hands, and especially since Sha'ul was a Rodef, who may be killed.
Why is it written Oyvecha, and we pronounce it Oyivcha?
Radak: Refer to 24:4:1:1.
What is the meaning of "Yitev"?
Radak: (Will be good.) It is written with only the Yud due to the conjugation; the Yud of the root is omitted.
What was the consequence of cutting the corner of the garment?
Radak citing Brachos 62b: Anyone who disgraces clothing, in the end he will not benefit from clothing -- "veha'Melech David... va'Yechasuhu ba'Begadim v'Lo Yicham Lo" (Melachim 1 1:1). Also refer to 24:5:1:4.
