Since the affirmation of the prophethood of the noble Messenger of Allah is also a major objective of the Holy Qur'an, it has been so asserted as and when the occasion warrants. That he is correctly reporting the event (in verses 246-251), while he neither learnt it from someone nor heard it anywhere nor saw it, is a miracle which is a sound proof of his prophethood. Al-Baqarah 2:252 ⧉ here (and Al-Baqarah 2:253 ⧉ which follows) demonstrate this proof.
It is being said here that these verses in which this event has been mentioned 'are the verses of Allah that We recite to you with all veracity' and this proves that you are certainly among the Messengers.'