Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates: In the time of the Messenger of Allah (peace and blessings be upon him) we used to say: "Who will be the most deserving of people for this matter (the caliphate)?" And we would say: "Abu Bakr." Then we would say: "Tell us, if Abu Bakr passes away, who will be the most deserving of people for this matter?" And we would say: "Umar bin al-Khattab." Then we would say: "Tell us, if Umar bin al-Khattab passes away, who will be the most deserving of people for this matter?" And we would say: "Uthman."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13334