Mishkat al-Masabih 30 Fine Qualities كتاب المناقب 132

وَعَن ابْن أبي مليكَة قَالَ: سَمِعْتُ عَائِشَةَ وَسُئِلَتْ: مَنْ كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مُسْتَخْلِفًا لَوِ اسْتَخْلَفَهُ؟ قَالَت: أَبُو بكر. فَقيل: ثُمَّ مَنْ بَعْدَ أَبِي بَكْرٍ؟ قَالَتْ: عُمَرُ. قِيلَ: مَنْ بَعْدَ عُمَرَ؟ قَالَتْ: أَبُو عُبَيْدَةَ بن الْجراح. رَوَاهُ مُسلم

Ibn Abu Mulaika told that when `A’isha was asked whom God’s messenger would have appointed successor if he had appointed one, he heard her say it would have been Abu Bakr. She was asked who it would have been after Abu Bakr and replied that it would have been `Umar. She was asked who it would have been after `Umar and replied that it would have been Abu `Ubaida b. al-Jarrah. Muslim transmitted it.