Sunan Ibn Majah Book 20, Hadith 2553

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَمُحَمَّدُ بْنُ الصَّبَّاحِ، قَالاَ حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ عُمَرُ بْنُ الْخَطَّابِ لَقَدْ خَشِيتُ أَنْ يَطُولَ، بِالنَّاسِ زَمَانٌ حَتَّى يَقُولَ قَائِلٌ مَا أَجِدُ الرَّجْمَ فِي كِتَابِ اللَّهِ فَيَضِلُّوا بِتَرْكِ فَرِيضَةٍ مِنْ فَرَائِضِ اللَّهِ أَلاَ وَإِنَّ الرَّجْمَ حَقٌّ إِذَا أُحْصِنَ الرَّجُلُ وَقَامَتِ الْبَيِّنَةُ أَوْ كَانَ حَمْلٌ أَوِ اعْتِرَافٌ وَقَدْ قَرَأْتُهَا الشَّيْخُ وَالشَّيْخَةُ إِذَا زَنَيَا فَارْجُمُوهُمَا الْبَتَّةَ ‏.‏ رَجَمَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَرَجَمْنَا بَعْدَهُ ‏.‏

It was narrated from Ibn`Abbas that `Umar bin Khattab said:“I fear that after a long time has passed, some will say: 'I do not find (the sentence of) stoning in the Book of Allah (ﷺ),' and they will go astray by abandoning one of the obligations enjoined by Allah (SWT). Rather stoning is a must if a man is married (or previously married) and proof is established, or if pregnancy results or if he admits it. I have read it (in the Quran). “And if an old man and an old woman commit adultery, stone them both.” The Messenger of Allah (ﷺ) stoned (adulterers) and we stoned (them) after him.' ”