In this reading, the verb is attributed to an unnamed caller, and the pronoun could refer back "Our spirit" (i.e. the Angel Gabriel) or to the child Mary had borne (in the verb ḥamalat'hu).
مَنْ تَحْتَهَا
man taḥtahā
“the one below her called out to her”
In this reading, the subject of the verb is this phrase "the one below her", implying that this caller should be known to be in that position.
Explanation
There are two standard opinions in exegesis: the caller was either the Angel who had stationed himself somewhere lower than Mary, or the baby who had just been born, and began his miraculous speech at this point. Each of the readings may be interpreted in accordance with these opinions [Makki].
He has revealed to you ˹O Prophet˺ the Book in truth, confirming what came before it, as He revealed the Torah and the Gospel
Explanation
There are two standard opinions in exegesis: the caller was either the Angel who had stationed himself somewhere lower than Mary, or the baby who had just been born, and began his miraculous speech at this point. Each of the readings may be interpreted in accordance with these opinions [Makki].