There are earlier citations for Presidents Monroe and Jackson and Senator Houston but, so far, it's unrecoverable speeches, letters &c quoted third-hand, much after the fact. No treaties at all.

One thing that seems universally lacking in the academic discussion of "how long is that?" is the ultimate source of the expressions (and wind, water and grass ftm.) One would think it be Psalms:

"Sing unto the Lord with thanksgiving, sing praise upon the harp unto our God:

Who covereth the heaven with clouds, who prepareth rain for the earth, who maketh grass to grow upon the mountains.

...he causeth the wind to blow, and the waters to flow." [147: 7-8, 18]


Taken in context it means less "forever & ever" than a somewhat more humble B'ezrat HaShem, Inshallah, Lord willing and the Creek don't rise &c.