Musnad Abu Ya'la al-Mawsili 129:13

Abu Bakr narrated to us, Abu Khalid al-Ahmar narrated to us, from Humayd, from Anas, who attributed it to the Prophet (ﷺ), he said: A woman came to him whose son had been killed, and she had no other son besides him, and his name was Harithah. She said: "O Messenger of Allah, if he is in Paradise, I will be patient, but if it is otherwise, you will see what I shall do." The Messenger of Allah (ﷺ) said: "It is many gardens, and he is in the highest Firdaws."