And he doesn’t reflect according to his whims.
Messenger didn’t talk according to his whim and will, instead he was reflecting what Allah put to his heart through Angel Jibreel. Generally in Lord’s Book, the word ‘yanthikhu’ is used for reflecting the nonliving things. Since Messenger Muhammed is illiterate as explained in verse 62: 2, instead of using ‘saying’, it is used ‘reflecting’. It is told in verse 41: 21 that on the Day of Judgement the skins of disbelievers will reflect; and in verse 21: 63 it is told that Messenger Ibrahim told his people ‘if the idols can reflect, you ask them’. It is told about the literate believers in verse 36: 65 as ‘on the Day of Judgement Allah will put a seal upon their mouths, their hands will speak to Him, and their legs will witness to Him about what they had been earning’. See explanation 26: 192-193; 42: 52; and 45: 28-29.