“Your servants shall do as my master commands; our young ones, our wives, our cattle and all our animals will be there, in the cities of the Gilad, and your servants shall have all armed forces pass before G-d to wage war, as my master spoke of” (Bamidbar 32:25-27). How could the sons of Gad and R’uvein say that Moshe had “commanded them” to do this, if it was their idea to have their families and animals stay on the eastern side of the Jordan River while their soldiers crossed to help the rest of the nation fight on the western side? Also, why did they add “as my master spoke of” after having already said that Moshe had commanded them? And why the switch from the word “commanded” to “spoke of”?
Malbim and Or Hachayim suggest that the “commandment” they referred to wasn’t the part about having their soldiers cross over to fight while everyone (and everything) else from their Tribes stayed behind, but to the change in order from building structures for their animals first and then the ones for their families, which was their original plan (32:16), to first building for their families and then taking care of their animals, as Moshe told them to do (32:24, baruch she’kavanti, unless I had previously seen it, and forgotten that I had). [See page 5 of http://www.aishdas.org/ta/5765/matos.pdf for an explanation as to why they wanted to build enclosures for their animals first.] When they then said “as my master spoke of” they were referring to another difference between what they had offered to do and what Moshe agreed to; whereas they had said they would take up arms “before the Children of Israel” (24:17), Moshe phrased it as “taking up arms before G-d” (24:20 and 24:21), putting the focus on doing it for G-d and the way G-d wants/expects it to be done, rather than doing it for the nation and how they might want things done. They agreed to make G-d the focal point, “as Moshe had phrased it,” besides following what he had “commanded” regarding which structures to build first.
There is one more instance of the sons of Gad and R’uvein restating that their soldiers would cross over and fight with the rest of the nation, telling everyone (not just Moshe) that they will “do that which G-d has spoken” (32:31). Although the entire conversation had only been between Gad/R’uvein and Moshe, so there was nothing “spoken by G-d” for them to say they will obey Him, Rabbeinu Bachye (32:27) explains that since Moshe was filled with His divine spirit, and was only telling them what G-d wanted of them, doing as Moshe said was the same as following what G-d says. However, this conversation was only about being part of the fighting force; there is no mention (here) about which structures to build first. Based on the Malbim and Or Hachayim, the only other thing Moshe added was that the fighting be done “before G-d” rather than “before the Children of Israel” (which was included in what “G-d spoke”). If this is what is being referred to as having been “spoken by G-d” (and Rabbeinu Bachye does tell us that it refers to what Moshe spoke when explaining the words “Moshe spoke,” indicating that they are the same), it would mean that when the sons of Gad and R’uvein told the nation they will do what G-d told them to do, they were saying that G-d told them to focus on Him rather than on them. This is not just awkward because it was being said to the nation, but also because they would be saying that G-d told them to focus on G-d (as opposed to Moshe being the one who told them to focus on G-d).
Another way of explaining what Moshe had “spoken of” (which the sons of Gad and R’uvein said they would do) is that it refers not (just) to fighting “before G-d” (instead of “before the Children of Israel”), but to the very notion that they would join (and perhaps lead) the fighting, even though they would have already received their land. True, this idea was originally theirs, but once it was accepted by Moshe, it was something he had also “spoken about” (notice that the word used is “doveir” not “dibeir,” which is normally used). We are all inundated with the thoughts and ideas of others, but only those that resonate with us are accepted as being (possibly) correct. These become, to an extent, our own ideas. Not in the sense that we should take any credit for having been the originator of the thought expressed, but by merely repeating it (ideally with attribution) as if it has validity, we give it our personal “stamp of approval,” and others may now value it more knowing that we think it has value. In this case, Moshe accepting Gad/R’uvein suggestion gave it more legitimacy; by saying “as my master spoke of” they were expressing the fact that Moshe’s acceptance impacted its value.
According to this, an interesting progression took place. Something was suggested by Gad/R’uvein, which was accepted by Moshe, giving him partial “ownership.” And since Moshe was so “in sync” with what G-d was thinking (as it were) that his carefully-considered thoughts could be described as G-d’s, the sons of Gad and R’uvein end up describing their own idea as having been “spoken by G-d.”
The Midrash (Sh’mos Rabbah 20:14) tells us that G-d didn’t bring us straight into the Promised Land (after the exodus) because Canaan only had 10 portions; by bringing us through the desert, we were able to conquer the land east of the Jordan too (let’s put aside why we couldn’t have conquered the west side first and then the east side), giving us an additional two portions, enough for all 12 Tribes (with the land east of the Jordan designated for Gad, R’uvein and half of M’nashe). It would seem that even if Gad and R’uvein hadn’t asked for this land, they would have (eventually) received it as their portion (see http://rabbidmk.wordpress.com/2010/07/21/parashas-va-eschanan-5770). They knew it would eventually be theirs (see 32:4; “for it is a land [appropriate for] cattle, and your servants have cattle”), and were only asking that it become theirs now, rather than having to cross the Jordan with their families and belongings just to cross back over (with their families and belongings) after everything was conquered and distributed. This is why, when the lottery that determined which portion of land went to each Tribe was drawn, all 12 Tribes were represented (see Rashi on Bamidbar 26:54), not just the 10 whose lands had not yet been specified. It is also why Moshe gave half of M’nashe their land now even though they hadn’t asked for it; since both Moshe and M’nashe knew it would eventually be theirs, how could Moshe make them schlep everything back and forth if Gad and R’uvein didn’t have to?
From this perspective, it was only the timing that was under discussion, not which land they would eventually get. When Moshe was making it official, though, he added a new, very significant, wrinkle; “if they do not cross over armed (i.e. ready to fight) with you (the rest of the nation), they will inherit amongst you in the Land of Canaan” (32:30). Were the sons of Gad and R’uvein willing to risk losing their rightful inheritance if they didn’t keep their commitment? They responded by saying “that which G-d has spoken, so shall we do” (32:31). They weren’t just referring to their previous commitment to join (or lead) the fight with the rest of their nation. If Moshe said the consequences of not doing so would be to lose their inheritance (and likely be “guests” among the other Tribes, similar to the way the Tribe of Shimon dwelled within the Tribe of Y’hudah), this must be what G-d had told him the consequences would be (see 32:23). Gad and R’uvein were acknowledging this as they accepted the conditions for being able to get their portions now. They would build protective houses for their families before building enclosures for their animals, as Moshe had commanded. They would fight with the rest of the nation, focusing on G-d in the process, as Moshe had spoken of. And they accepted the consequences for not doing so, as G-d had spoken.