Jami` at-Tirmidhi, Volume 4, Book 31, Hadith 2225 (DarusSalam) ⓘ
Salim bin 'Abdullah narrated from his father who said: "It was said to 'Umar bin Al-Khattab: 'Perhaps you should endorse your successor.' He said: 'If I appoint a successor, then indeed Abu Bakr appointed a successor. And if I do not appoint a successor, the Messenger of Allah(s.a.w) did not appoint a successor."'
حَدَّثَنَا يَحْيَى بْنُ مُوسَى، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمِ بْنِ عَبْدِ اللَّهِ بْنِ عُمَرَ، عَنْ أَبِيهِ، قَالَ قِيلَ لِعُمَرَ بْنِ الْخَطَّابِ لَوِ اسْتَخْلَفْتَ قَالَ إِنْ أَسْتَخْلِفْ فَقَدِ اسْتَخْلَفَ أَبُو بَكْرٍ وَإِنْ لَمْ أَسْتَخْلِفْ لَمْ يَسْتَخْلِفْ رَسُولُ اللَّهِ صلى الله عليه وسلم . قَالَ أَبُو عِيسَى وَفِي الْحَدِيثِ قِصَّةٌ طَوِيلَةٌ . وَهَذَا حَدِيثٌ صَحِيحٌ قَدْ رُوِيَ مِنْ غَيْرِ وَجْهٍ عَنِ ابْنِ عُمَرَ .
also referenced under: Hadith 2225 (Reference) & Book 33, Hadith 68 (In-Book)