Why does it say "Amar', and not va'Yomer?
Malbim: When the verses tell a story in order, the verb is in future conjugation with the prefix Vov to denote the past. If it is out of order (it relates an action before the last matter), it uses the simple past tense, and the subject precedes the verb (past participle
Hashem knew that he would be afraid even before he spoke to Bnei Gad and Bnei Reuven and sent spies! Perhaps the verse hints to why Hashem spoke to him (but had he not feared, Hashem would not have spoken to him). Alternatively, Hashem waited until he sent spies, so they will need to spare Rachav, from whom Yirmeyah and other Nevi'im would descend (Megilah 14b). (PF)
Why would he rely on them more than on Bnei Gad? Moshe blessed that Gad will cut off the arm [of Kena'anim] together with the head (Devarim 33:20)! Perhaps Malbim means Reuven and Gad. Or, this is like Bava Kama 92a, that Reuven was [even] stronger than Gad (refer to Bereishis 47:2:1:2). (PF)
