Al-Agharr Abu Malik said: When Sayyiduna Abu Bakr (may Allah be pleased with him) intended to appoint Sayyiduna Umar (may Allah be pleased with him) as caliph, he sent for him and called him. When he came to him, Sayyiduna Abu Bakr (may Allah be pleased with him) said: "I am going to call you to a matter that will weary whoever takes charge of it. O Umar! Fear Allah Almighty through obedience to Him, and obey Him through being mindful of Him, for God-consciousness is a protected thing. Then, after that, there is the matter (of authority): only the one who acts upon it makes it his due. Whoever commands according to the truth but acts according to falsehood, or commands good but does evil, his hopes will soon be cut off and his deeds will be wasted. When you become the custodian of their affairs, then, if you are able, keep your hands free of their blood, keep your stomach clear of their wealth, and keep your tongue away from their honour; do so. And nothing happens without the help of Allah Almighty."
Al-Tabarani recorded it. The narrator al-Agharr did not live in the time of Sayyiduna Abu Bakr (may Allah be pleased with him); the rest of its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الخلافة / 9008