Musnad Abu Ya'la al-Mawsili 6:9

Abu Khaythama narrated to us, Muhammad ibn al-Hasan ibn Abi al-Hasan al-Madani narrated to us, 'Abd al-'Aziz ibn Muhammad narrated to me, from Suhayl ibn Abi Salih, from Muhammad ibn Muslim ibn 'A'idh, from 'Amir ibn Sa'd, from Sa'd ibn Abi Waqqas: That a man came to the prayer while the Messenger of Allah (may Allah bless him and grant him peace) was praying. When he reached the row, he said, "O Allah, give me the best of what You give to Your righteous servants." When the Messenger of Allah (may Allah bless him and grant him peace) finished the prayer, he said, "Who was the speaker just now?" The man said, "I was, O Messenger of Allah." He said, "Then your horse will be hamstrung, and you will be martyred in the way of Allah."