Musnad Ahmad 1235:1

Hammad ibn Mas'adah narrated to us, he said: Ibn Jurayj narrated to us, from Abu al-Zubayr, from 'Umar ibn Nabhan, from Abu Tha'labah al-Ashja'i, who said: I said: "O Messenger of Allah, two of my children died in Islam." He said: "Whoever has two children die in Islam, Allah, the Almighty and Majestic, will cause him to enter Paradise by the grace of His mercy upon them." He said: Then, after that, Abu Hurayrah met me and said: "Are you the one to whom the Messenger of Allah, peace and blessings of Allah be upon him, said regarding the two children what he said?" I said: "Yes." He said: "For him to have said that to me would be more beloved to me than everything upon which Homs and Palestine are closed."