When explaing G-d's command to Balak, in B'midbar 22:38, Bilam says "what G-d places in my mouth is what I shall speak."
In B'midbar 23:12, his phrasing is, "... Whatever G-d places in my mouth is what I will watch to speak." (in Heb. אותו אשמור לדבר) (My own English translation.)
The phrasing in the 2nd verse appears "extra". What does Bilam mean by "watching to speak?" Why not just phrase it similarly to the 1st phrasing? Once G-d has placed words in his mouth, doesn't that imply that he is already speaking and under G-d's control and no longer under his own control, anyway? How can he "watch" what he says at that point?