Musnad Abu Ya'la al-Mawsili 155:228

And by the same chain from Abu Hurairah, that a woman came to the Prophet, may Allah bless him and grant him peace, and with her was a son of hers who was ill. She said, "O Messenger of Allah, supplicate to Allah to heal this son of mine." He said, so the Messenger of Allah, may Allah bless him and grant him peace, said to her, "Do you have a 'farat' (a child who has passed away before you)?" She said, "Yes, O Messenger of Allah." He said, "In the pre-Islamic period or in Islam?" She said, "Rather, in Islam." He said, "A fortified shield, a fortified shield, a fortified shield."