Musnad Abu Ya'la al-Mawsili 152:17

Abu Hisham al-Rifa'i narrated to us, al-Walid ibn 'Uqbah al-Shaybani narrated to us, Za'idah narrated to us, from 'Asim, from Abu Wa'il, from 'Abdullah, who said: The Messenger of Allah (may Allah bless him and grant him peace) went out to the mosque, and there were women from the Ansar in it. He came to them, exhorted them, and reminded them. He said: "There is no woman among you whose three children die, except that she will enter Paradise." A woman from among the best of them said: "O Messenger of Allah, what about one who has two?" He said: "There is no woman among you whose two children die, except that she will enter Paradise."