وَالسَّلَامُ عَلَيَّ يَوْمَ وُلِدتُّ وَيَوْمَ أَمُوتُ وَيَوْمَ أُبْعَثُ حَيًّا

In spite of Mary’s pointing toward the child, the people could not understand how they were supposed to talk to a small child. At that time, the child himself started speaking. In his miraculous utterances, there was, on the one hand, complete absolution of Mary and, on the other, advance evidence of his prophethood, so that when he grew up and declared his prophethood, there should be no scope for any doubt about it.

— Source: Tazkirul Quran (Maulana Wahiduddin Khan) via Quran.com (19:33)