She simply pointed her finger at him -the babe- with an intimation,

﴿فَأَشَارَتۡ إِلَيۡهِۖ قَالُواْ كَيۡفَ نُكَلِّمُ مَن كَانَ فِي ٱلۡمَهۡدِ صَبِيّٗا ﴾
[مَريَم: 29]

She simply pointed her finger at him -the babe- with an intimation, as it were, that they ask or speak to him. But they exclaimed: "How in Allah's Name can we discourse with a new born babe

﴿فأشارت إليه قالوا كيف نكلم من كان في المهد صبيا﴾ [مَريَم: 29]

Dr Kamal Omar
Then she pointed to him. People said: “How we would talk to that who is a baby in the lap?”

Dr Laleh Bakhtiar
Then, she pointed to him. They said: How speak we to one who had been in the cradle, a lad

Dr Munir Munshey
She pointed towards the infant. They said, "How can we converse with an infant lying in a crib

Edward Henry Palmer
And she pointed to him, and they said, 'How are we to speak with one who is in the cradle a child

Farook Malik
In response she merely pointed towards the baby. They said: "How can we talk to a babe in the cradle

George Sale
But she made signs unto the child to answer them; and they said, how shall we speak to him, who is an infant in the cradle

Maududi
Thereupon Mary pointed to the child. They exclaimed: "How can we speak to one who is in the cradle, a mere child