Allah says here:

أَنَّى لَهُمُ الذِّكْرَى وَقَدْ جَاءهُمْ رَسُولٌ مُّبِينٌ ﴿١٣﴾

ثُمَّ تَوَلَّوْا عَنْهُ وَقَالُوا مُعَلَّمٌ مَّجْنُونٌ ﴿١٤﴾

How can there be for them an admonition, when a Messenger explaining things clearly has already come to them. Then they had turned away from him and said:

"(He is) one taught, a madman!''

meaning, `what further admonition do they need when We have sent them a Messenger with a clear Message and warning? Yet despite that, they turned away from him, opposed him and rejected him, and they said: (He is) one taught (by a human being), a madman.'

This is like the Ayah:

يَوْمَئِذٍ يَتَذَكَّرُ الإِنسَـنُ وَأَنَّى لَهُ الذِّكْرَى

On that Day will man remember, but how will that remembrance (then) avail him? (89:23)

وَلَوْ تَرَى إِذْ فَزِعُواْ فَلاَ فَوْتَ وَأُخِذُواْ مِن مَّكَانٍ قَرِيبٍ

وَقَالُواْ ءَامَنَّا بِهِ وَأَنَّى لَهُمُ التَّنَاوُشُ مِن مَّكَانِ بَعِيدٍ

And if you could but see, when they will be terrified with no escape, and they will be seized from a near place.

And they will say (in the Hereafter): "We do believe (now);'' but how could they receive (faith and its acceptance by Allah) from a place so far off... (34:51-52)