Narrated Ibn 'Umar:
'Umar said: I shall not appoint a successor, for the Messenger of Allah ﷺ did not appoint a successor. If I appoint a successor (I can do so), for Abu Bakr had appointed a successor. He Ibn 'Umar) said: I swear by Allah, he did not mention (anyone) but the Messenger of Allah ﷺ and Abu Bakr. So I learnt he would not equate anyone with the Messenger of Allah ﷺ, for he did not appoint any successor.

حَدَّثَنَا مُحَمَّدُ بْنُ دَاوُدَ بْنِ سُفْيَانَ، وَسَلَمَةُ، قَالاَ حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ عُمَرُ إِنِّي إِنْ لاَ أَسْتَخْلِفْ فَإِنَّ رَسُولَ اللَّهِ ﷺ لَمْ يَسْتَخْلِفْ وَإِنْ أَسْتَخْلِفْ فَإِنَّ أَبَا بَكْرٍ قَدِ اسْتَخْلَفَ . قَالَ فَوَاللَّهِ مَا هُوَ إِلاَّ أَنْ ذَكَرَ رَسُولَ اللَّهِ ﷺ وَأَبَا بَكْرٍ فَعَلِمْتُ أَنَّهُ لاَ يَعْدِلُ بِرَسُولِ اللَّهِ ﷺ أَحَدًا وَأَنَّهُ غَيْرُ مُسْتَخْلِفٍ .