1)
What is "u'va'Davar ha'Zeh" referring to?
1.
Rashi: It is referring to Hashem's promise to bring them into Eretz Cana'an, which they declined to believe.
2.
Oznayim la'Torah: Refer to 1:31:1:2. 'And in this context - that Hashem carriied you like a father carries his son (Pasuk 23 - when He went before you in a Pillar of Fire by night, and in a Pillar of Cloud by day to seek for you a place to rest) you do not believe in Him!'