It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "The gentlest of my Ummah is Abu Bakr (may Allah be pleased with him), the sternest in the religion of Allah is Umar (may Allah be pleased with him), the most genuine in modesty is Uthman (may Allah be pleased with him), Zayd (may Allah be pleased with him) is the most expert in the knowledge of the fara'id (laws of inheritance), Ubayy (may Allah be pleased with him) is the best reciter, and the most knowledgeable about the lawful and the unlawful is Mu'adh (may Allah be pleased with him). Every nation has a trustee, and the trustee of this Ummah is Abu Ubaydah bin al-Jarrah (may Allah be pleased with him)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الفرائض / 12187