Muhammad ibn al-Husayn, from Ibn Abi Umayr, from Muawiyah ibn Ammar, who said:
I (narrator) asked Abu Abdillah عليه السلام, peace be upon him, about ‘a newborn who was born on the night of Eid al-Fitr, Is there fitrah upon him?’ Imam عليه السلام said: “No, he has already exited the month.”
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 4, p. 413