If you hadn't brought them any verse, they would ask: "Why didn't you get It together?" You say: "Indeed, I follow what has been inspired into me from my Lord, this is an Insight from your Lord, the Guidance and Mercy for the believing people.
Verses of the Lord’s Book were sent down step by step within 23 years. And it was not codified as a Book during Messenger Muhammad's time. So the disbelievers were asking him why these verses are not sent down to him at a time as a codified book. Messenger is commanded to tell them that he is following what has been inspired to him by the Lord.
After the codification of the Lord’s Book which contains 6236 verses, It is the Insight for the entire mankind as explained in verses 3: 4 and 6: 104. It is the Guidance and Mercy for the believing people as explained in verse 7: 52. It is the Splendid Book which contains all 312 previous Books and their upright Explanations as explained in verse 16: 44.
Today Adhikr is codified through the Three-Time-Knower mentioned in verse 25: 59. But the Fujjar are not utilizing It or are not giving It to others so that they will be dragged into Hell prone on their faces, and they are in the worst place and they are the most strayed as explained in verses 25: 33-34. See explanation 2: 23-24 and 6: 155-157.