Syedna Ali (may Allah be pleased with him) narrates that when the Prophet (peace and blessings be upon him) sent me to Yemen, I was young at that time. I said to the Prophet (peace and blessings be upon him), "I am young and I have absolutely no knowledge of making judgments." The Prophet (peace and blessings be upon him) struck his hand on my chest and said: "Allah will guide your tongue to the right path and will keep your heart firm." Syedna Ali (may Allah be pleased with him) says that after that, I never had any doubt in making judgments between two people.
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 1145
Hadith Gradingحکم دارالسلام:صحيح لغيره، وهذا إسناد ضعيف لجهالة الواسطة بين أبى البختري و بين علي