When Maryam (peace be upon her) delivered Jesus and brought him to her people, they spoke in astonishment, making great this matter and declaring to her that her parents were not impious people. Here is the Qur'anic account:

Then she brought him (the baby) to her people, carrying him. They said: "O Mary! Indeed you have brought a thing an unheard mighty thing. O sister of Harun (Aaron)! Your father was not a man who used to commit adultery, nor was your mother an unchaste woman."(Maryam 19:27-28)

The question arises here as to why was Maryam (peace be upon her) addressed by her people as "sister of Aaron." The Muslim exegetes have cited two explanations for this:

The first is that Harun (Aaron) was the name given to righteous people amongst them, because of a man amongst them called Harun who was very righteous. So when she brought the baby, they said to her "O sister of Harun", meaning "O one who is associated with rectitude, righteousness" because she came from a righteous family. Al-Tabari mentions this view from Qataadah (an early commentator of the Qur'an who studied with the Prophet's companions), and Muhammad bin Seereen and others. Al-Baghawi mentions that Qataadah and others stated that Aaron was a righteous worshipper and that forty-thousand people followed his funeral the day that he died and all of them were called Aaron. This name therefore was associated with piety and righteousness and hence, the use of the phrase "O sister of..." is not referring to blood relationship. This is like the saying of Allaah, "Verily, the spendthrifts (those who squander wealth) are the brethren of the devils..." (17:27). Al-Baghawi also cites a narration from al-Kalbi that Aaron referred to here was a brother of Maryam through her father, and he was the most righteous man amongst Bani Isra'eel in that time. Ibn Kathir supports this view and cites from al-Tabari in this regard. And Imaam al-Sa'dee from the contemporary Scholars of Ahl al-Sunnah (those adhering to the Prophetic tradition) also supports the view that this statement is referring to an actual brother of Mary called Aaron, and that the Bani Israa'eel used to call their children by the names of former prophets.

The second is that is indeed Harun (Aaron) the brother of Moses, and Maryam was from his lineage, and thus it was said to her "O sister of Aaron" just like it is said to one who belongs to a tribe, "O brother of the tribe" such as for example one who is a Tamimi (of the Tameem tribe), "O brother of Tameem" and to the Mudarree (of the Mudarr tribe), "O brother of Mudarr." Al-Tabari mentions this view from al-Sudee (another early Qur'anic exegete).

The first is the most correct view, and when we read the remainder of the verse, "Your father was not a man who used to commit adultery, nor was your mother an unchaste woman..." we see that the people were protesting the fact that she was the sister of a very righteous man and her father and mother were not impious, so on all these three counts, how has she come with a baby, when all of her family members (father, mother, brother) are associated and known for piety and righteousness? Maryam (peace be upon her) did not speak and simply pointed to the child, and we shall take this matter up in a separate article, and this is from the miracles of Eesaa (peace be upon him) in that he spoke as an infant and defended his mother's honour and reputation.