From Sahih Bukhari (Hadith 3982):
Narrated Anas:Haritha was martyred on the day (of the battle) of Badr, and he was a young boy then. His mother came to the Prophet (ﷺ) and said, "O Allah's Messenger (ﷺ)! You know how dear Haritha is to me. If he is in Paradise, I shall remain patient, and hope for reward from Allah, but if it is not so, then you shall see what I do?" He said, "May Allah be merciful to you! Have you lost your senses? Do you think there is only one Paradise? There are many Paradises and your son is in the (most superior) Paradise of Al- Firdaus
Reference: Bukhari 3982