Musnad Abu Ya'la al-Mawsili 134:12

'Abd al-Rahman ibn Salih al-Azdi narrated to us, Yahya ibn Ya'la al-Aslami narrated to us, from al-A'mash, from Anas, who said: A boy from among us was martyred on the day of Uhud, and a rock was found tied to his stomach due to hunger. His mother wiped the dust from his face and said, "Congratulations to you, my son, for Paradise." The Prophet, peace and blessings of Allah be upon him, said, "What makes you know? Perhaps he used to speak about that which did not concern him, and withhold that which did not harm him."