بسم الله الرحمن اللرحيم
It is well known and mentioned in many places that the first words of Jesus عليه السلام were, "I am Abdullah"
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Darul Uloom Bury for example, have this too http://www.inter-islam.org/Biographies/Hazisa78.html where it is mentioned:
Imam Qurtubi has stated, "The very first words spoken by Jesus in the cradle, indicated that he would uphold a lofty status and be awarded remarkable attributes, as he said :
"I am indeed a servant of Allah. He has given me the book and made me a prophet and made me blessed wherever I shall be and enjoined upon me prayer and charity, as long as I live and made me obedient to my mother and He has not made me overbearing or miserable." 19/32.
Is this Specific to those words spoken in the presence of others (i.e. from the cradle) because the verses before that say that he told his mother from below:
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So she conceived him, and she withdrew with him to a remote place.
And the pains of childbirth drove her to the trunk of a palm tree. She said, "Oh, I wish I had died before this and was in oblivion, forgotten."
But he called her from below her, "Do not grieve; your Lord has provided beneath you a stream.
And shake toward you the trunk of the palm tree; it will drop upon you ripe, fresh dates.
So eat and drink and be contented. And if you see from among humanity anyone, say, 'Indeed, I have vowed to the Most Merciful abstention, so I will not speak today to [any] man.' "
Then she brought him to her people, carrying him. They said, "O Mary, you have certainly done a thing unprecedented.
O sister of Aaron, your father was not a man of evil, nor was your mother unchaste."
So she pointed to him. They said, "How can we speak to one who is in the cradle a child?"
[Jesus] said, "Indeed, I am the servant of Allah . He has given me the Scripture and made me a prophet.
And He has made me blessed wherever I am and has enjoined upon me prayer and zakah as long as I remain alive
And [made me] dutiful to my mother, and He has not made me a wretched tyrant.
And peace is on me the day I was born and the day I will die and the day I am raised alive."
That is Jesus, the son of Mary - the word of truth about which they are in dispute.
So the first words were Laa Tahzan - Do not despair? It's a little confusing, because in other translations it says that Eesa (as) said it and in other places, it says that Jibreel (as) said it.

Then (one) called out to her from beneath her, "Do not grieve. Your Lord has already made beneath you a rivulet.
If this is one of those ambigous verses, it would be safer just to say that the first words "from the cradle" were...

He said, "Surely I am the bondman of Allah. He has brought me the Book and made me a Prophet.
