Sayyiduna Mus'ab al-Aslami (may Allah be pleased with him) said: A boy from among us went to the Prophet (peace and blessings be upon him) and said: "I want to ask you something." He (peace and blessings be upon him) said: "What is it?" He said: "I ask you to make me among those for whom you will intercede on the Day of Resurrection." He (peace and blessings be upon him) said: "Who told you to ask this - or who taught you this - or who guided you to this?" He said: "No one told me; my own heart desired it." He (peace and blessings be upon him) said: "Then you are among those for whom I will intercede on the Day of Resurrection." The boy set off joyfully to tell his family, but when he turned away, he (peace and blessings be upon him) said: "Bring the boy back to me." They brought him back in a sorrowful state, fearing that something had happened concerning him. He (peace and blessings be upon him) said: "Help me in interceding for yourself by prostrating much."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17976