Sunan Abi Dawud 25224
In-book no 4720حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا حَمَّادٌ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ، أَنَّ رَجُلاً، قَالَ يَا رَسُولَ اللَّهِ أَيْنَ أَبِي قَالَ " أَبُوكَ فِي النَّارِ " . فَلَمَّا قَفَّى قَالَ " إِنَّ أَبِي وَأَبَاكَ فِي النَّارِ " .
Anas said : A man asked : where is my father, Messenger of Allah? He replied! Your father is in Hell. When he turned his back, he said : My father and your father are in Hell.