I should've known that was too easy. Isaiah 44:6?
Thus says Yahweh, the king of Israel,
and its redeemer, Yahweh of hosts:
"I am the first, and I am the last,
and there is no god besides me."
The context being that He is saying there are none like Him, not that there is no God as in no divine being (and even in the verse it says "besides me"), for it goes on in verse 7 and verse 8:
"And who is like me? Let him proclaim it!
And let him declare it and set it in order for me
since I established an eternal people and things that are to come,
and let them tell them the things that are coming.
You must not tremble,
and you must not be paralyzed with fear.
Have I not made you hear from of old
and declared it, and you are my witnesses?
Is there a god besides me?
And there is no rock! I know none!"
I doubt it is this one also (but worth a shot) and so will think far longer for my next context search. Extremely good thread.