The firmness of Umar (may Allah be pleased with him) for the sake of Allah and his hatred of falsehood

Umar bin Rabi'ah narrates: Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) sent for Ka'b al-Ahbar and asked: "O Ka'b! How have you found my description?" He said: "I have found your description to be that you are a horn of iron." Sayyiduna Umar (may Allah be pleased with him) asked: "What is meant by a horn of iron?" Ka'b said: "A ruler who will be firm; the blame of any blamer will not take hold of him in the matter of Allah Almighty." Sayyiduna Umar (may Allah be pleased with him) asked: "And what else?" He said: "And that after you there will be a caliph whom a wrongdoing group will kill." Sayyiduna Umar (may Allah be pleased with him) asked: "Then what will happen?" Ka'b said: "After that there will be trials."
Tabarani recorded it, and its narrators are thiqat (trustworthy).

Sayyiduna al-Aswad bin Sari' (may Allah be pleased with him) narrates: I came to the Prophet (peace and blessings be upon him) and said: "O Messenger of Allah! I have praised my Lord with some words, and I have said some words in praise of you." The Prophet (peace and blessings be upon him) said: "As for your Lord, He loves praise. Present the words with which you have praised your Lord." The narrator says: So I began reciting my verses. Meanwhile a man came and asked permission to enter. He was a tall man of tawny complexion, whose hair was gone, and who used his left hand more than his right. The narrator says: The Prophet (peace and blessings be upon him) told me to be silent. Here the narrator Abu Salamah demonstrated how the Prophet (peace and blessings be upon him) had silenced him, the way it is done with a cat. Then that man came, talked for a while, and then left. Then I began reciting verses to the Prophet (peace and blessings be upon him) again. After a while that man came back, and the Prophet (peace and blessings be upon him) again made me fall silent; here too the narrator demonstrated how he had silenced him. I said: "Who was this man for whose sake you made me fall silent?" The Prophet (peace and blessings be upon him) said: "This is a man who does not love falsehood. This is Umar bin al-Khattab."
Ahmad recorded it, and Tabarani recorded something similar, in which his words are: A man came in who was tall, with a raised nose, and the Prophet (peace and blessings be upon him) said to me: "Be silent."

In a narration recorded by him the words are: A man came in who was broad-chested. In this narration these words are added: I was told that this was Sayyiduna Umar bin al-Khattab (may Allah be pleased with him). By Allah! Later I came to know that it would not have been difficult for him, if he heard me saying something (wrong), to seize me by the foot without speaking a word to me and drag me off to al-Baqi'. The narrators of both these narrations are thiqat (trustworthy), and there is disagreement about some of its narrators.