Muhammad bin Yahya bin Hayan narrated that indeed a man narrated to him from his father Yahya that he was with Ibn Umar (may Allah be pleased with them both), so Ibn Umar (may Allah be pleased with them both) said to him: "You do not consider killing during tribulation to be anything, and the Messenger of Allah (peace and blessings be upon him) has said: 'Two people should not whisper together excluding a third.'"