Say, "If the sea were ink for the Words of my Lord, the sea would run
before the Words of my Lord run out, even if We were to
supply the same amount of ink as a supplement.


Perhaps much of the relevance of this glorious verse is intended to silence those who despite God's description of the Quran as fully detailed (6:114), still claim that the Quran does not include all the details of the religion! These Quranic words address these people and inform them that if the religion prescribed for them in the Quran was in need of more details or words, that God would have added more words to the Quran, for after all God is never short of words.
The words in 18:109 are also directed to the interpreters who deliberately add words to God's words, which categorically change the meaning, then say "this is what is meant by the verse". By doing so, they are indirectly implying that God is not efficient in expressing a specific meaning, and that only through their expert addition of words (to the original text) are we able to understand the mysterious Quran!

These glorious words tell us that God's Words are endless, and that if He saw wisdom in adding more words to any Quranic verse then He would have easily done so. For God is never short of words.