Musnad Ahmad 30:1702

Yahya ibn Ishaq narrated to us, al-Bara’ informed us, from al-Hasan, from Abu Hurayrah, who said: My intimate friend, the truthful one, the Messenger of Allah (may Allah bless him and grant him peace), narrated to me that he said: "There will be in this nation an expedition to Sindh and Hind. If I live to see it and am martyred, then that is it. And if I return—and he mentioned a word—I will be Abu Hurayrah, the freed one, for He has freed me from the Fire."