Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said that it was said to Sayyiduna Umar (may Allah be pleased with him): Will you not nominate (someone as) successor? He said: "If I leave (the matter), then one better than me left it before me, namely the Messenger of Allah (peace and blessings be upon him); and if I nominate, then Sayyiduna Abu Bakr (may Allah be pleased with him), who was better than me, nominated before me." (Sayyiduna Abdullah bin Umar (may Allah be pleased with them both)) said: They praised him, and he said: "With hope and with fear. I will not bear it, neither in life nor after death. I only wish that I could be released from it (on equal terms), with nothing for me (in reward) and nothing against me (as a burden)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قتال أهل البغي / 16570