Hisham bin Urwah narrated from his father (Urwah) that a man asked Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) about an issue, so he said: I do not know about it. When that man left, Sayyiduna Ibn Umar (may Allah be pleased with them both) said: What Ibn Umar said was correct; he was asked about something he did not know, so he said: I do not know about it.