Musnad Ahmad 332
It was narrated from Salim from Ibn ‘Umar that he said to `Umar:
I heard the people saying something so I decided that I should talk to you. They are saying that you are not going to appoint a successor. He lowered his head for a while, then he looked up and said: Allah, may He be glorified and exalted, will protect His religion. If I do not appoint a successor, the Messenger of Allah (ﷺ) did not appoint a successor either; if I do appoint a successor, Abu Bakr appointed a successor. By Allah, once he mentioned the Messenger of Allah (ﷺ) and Abu Bakr, I realized that he was not going to regard anyone else as equal to the Messenger of Allah (ﷺ) and that he was not going to appoint a successor.
حَدَّثَنَا عَبْدُ الرَّزَّاقِ، حَدَّثَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنِ ابْنِ عُمَرَ، رَضِيَ اللَّهُ عَنْهُ أَنَّهُ قَالَ لِعُمَرَ رَضِيَ اللَّهُ عَنْهُ إِنِّي سَمِعْتُ النَّاسَ يَقُولُونَ مَقَالَةً فَآلَيْتُ أَنْ أَقُولَهَا لَكُمْ زَعَمُوا أَنَّكَ غَيْرُ مُسْتَخْلِفٍ فَوَضَعَ رَأْسَهُ سَاعَةً ثُمَّ رَفَعَهُ فَقَالَ إِنَّ اللَّهَ عَزَّ وَجَلَّ يَحْفَظُ دِينَهُ وَإِنِّي إِنْ لَا أَسْتَخْلِفْ فَإِنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لَمْ يَسْتَخْلِفْ وَإِنْ أَسْتَخْلِفْ فَإِنَّ أَبَا بَكْرٍ رَضِيَ اللَّهُ عَنْهُ قَدْ اسْتَخْلَفَ قَالَ فَوَاللَّهِ مَا هُوَ إِلَّا أَنْ ذَكَرَ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَأَبَا بَكْرٍ فَعَلِمْتُ أَنَّهُ لَمْ يَكُنْ يَعْدِلُ بِرَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَحَدًا وَأَنَّهُ غَيْرُ مُسْتَخْلِفٍ‏.‏