The Cave - 18:109
"Say, "If the ocean were ink for the words of my Lord, and even if we added as much, the ocean would be exhausted before the words of my Lord are exhausted."
Related:
Luqman/31:27
If all the trees of the earth were pens, and seven seas were added to the seas, Allah´s words would not be exhausted. Allah is Exalted, Wise.