Musannaf Ibn Abi Shayba 18:1129

Abu Bakr narrated to us, he said: Ibn ‘Ulayyah narrated to us, from Yahya ibn Abi Ishaq, he said: I heard Salim ibn ‘Abdullah saying, while a group from Banu Layth were preparing to take an oath the next day regarding the *qasamah* (oath-taking in homicide cases): "O servants of Allah, look at a people who swear to that which they did not see, and were not present for, and did not witness. If I had any authority in the matter, I would have punished them, or I would have made an example of them, and I would not have accepted their testimony."