Source: Jaami’ Bayaan al-‘Ilm wa Fadhlihi v2 p117
mentions:
We were with Maalik ibn Anas رحمه الله when a man came saying: ‘O Abu ‘Abdullaah, I have travelled a distance of six months. The people of my land sent me to ask you about a matter.’
So he said: ‘Ask!’
So the man asked him some things, so he replied: ‘I do not know’
…and the man thought he had come to someone who knew everything, so he said: ‘What shall I tell the people of my land when I return to them?’
He said: ‘Say to them: Maalik ibn Anas does not know.’
