What is the connection between this Pasuk and the previous Pesukim?
Rashi: To inform the people that, despite the fact that they strayed from before Hashem and made the Golden Calf, Hashem instructed Moshe to lead them to Eretz Cana'an.
Ramban: Refer to 10:10:2:2*.
Why did Hashem mention inheriting the land without any reference to fighting for it?
Because, had they not sent the Meraglim, they would have taken over Eretz Cana'an without as much as raising a sword. Refer to Devarim, 1:8:2:1.
Why did Hashem see fit to mention the Shevu'ah here?
Seforno: Because, if not for the Shevu'ah, due to the constant rebellion of Yisrael, they would not have merited to inherit Eretz Yisrael.