Why does it say "me'Oscha"?
Radak: This is like "me'Itcha". There are many words that [should have a Dagesh, but] they are soft (without a Dagesh).
Why does it say here "b'Chesef Shekalim Chamishim", and in Divrei ha'Yamim I, 21:25, it says "Shiklei Zahav Mishkal Shesh Me'os"?
Rashi (citing Zevachim 116b, Sifri Devarim 62): David collected 50 Shekalim of silver from each Shevet, 600 in all, and gave to Aravnah for the value of [50 Shekalim of] gold.
Rashi (Zevachim 116b): He collected silver Shekalim from each Shevet worth 50 gold Shekalim. In all, he paid the value of 600 gold Shekalim.
Radak and Malbim, both from Zevachim 116b: He collected silver Shekalim from each Shevet, equated to were weight of 50 gold Shekalim (gold Shekalim do not weigh the same as silver Shekalim. Tosfos (Kesuvos 99a DH Nasan) - a gold Shekel weighs twice as much.)
Radak and Malbim (both citing Rebbi, Zevachim 116b): He paid 50 for the cattle, wood and place of the Mizbe'ach. 1 He paid 600 for the place of the entire Beis ha'Mikdash. 2
Malbim: First, he bought only the place of the Mizbe'ach. After [he offered Korbanos, and] fire descended from Shamayim, like it says in Divrei ha'Yamim I, 21:26, he knew that the place was chosen for the Beis ha'Mikdash, he bought also the place around it.
Radak: The verses support this. Here it mentions buying the cattle, wood and granary (where the Mizbe'ach would be) for 50. In Divrei ha'Yamim, it says he paid 600 for 'the place', i.e. of the entire Beis ha'Mikdash.
What is the significance of the plague ending in the place where the Beis ha'Mikdash will be built?
Malbim: From now was fulfilled Nasan's prophecy. War from the enemy ceased, like I wrote above (Perek 7); David began preparing the place for the Mikdash, and he did not need an army any more.
