He said: “I am indeed a servant of Allah: He hath given me revelation and made me a prophet;
(“I am the servant of Allah” – 19:30)
There is a report that when her family members started berating and censuring Sayyidah
Maryam (AS), Sayyidna ‘Isa (pbuh) was sucking milk. When he heard
their accusations he stopped sucking milk and moved over to his left side
facing them, and raising his index finger he said: i.e. I am the
servant of Allah. In this way in his very first words Sayyidna ‘Isa (pbuh)
made it clear that although his birth was a miracle, he himself was not
God, but only a servant of God. This was to eliminate forever the
possibility of people worshipping him as God due to his miraculous birth.
“He has given me the Book and made me a prophet.” – 19:30.
In these words, Sayyidna ‘Isa (pbuh) even in his infancy announced his
future prophethood and the revelation to him of a sacred book from Allah
Tala. Since no prophet has been granted prophethood and a sacred book
before the age of forty years, therefore this pre-announcement of his
prophethood by Sayyidna Isa (pbuh) here means to convey in advance
that he would be bestowed prophethood and the Book at the proper time.
In a similar manner The Holy Prophet (S) said that he was bestowed
prophethood even before Adam was yet in the process of his creation.
This shows that the promise for granting prophethood to Sayyidna
Muhammad Al-Mustafa (S) was firm and final. Here too, because of the
certainty of occurrence, the grant of prophethood is referred to in the past
tense. By announcing his future prophethood he (Sayyidna ‘Isa)
dispelled peoples’ doubts and exonerated his mother from the charge of
fornication, because his being a Prophet was proof enough that his birth
was free from any blemish.
Shafi, Muhammad (2008). Maariful Quran. (Vol .5 surah 19 verse 30). English-MaarifulQuran-MuftiShafiUsmaniRA-Vol-6.pdf (islamicweblibrary.com)