Musannaf Ibn Abi Shayba 38:84

Waki’ narrated to us, from al-A’mash, from ‘Amr ibn Murrah, from ‘Abdullah ibn Salamah, or from Abu al-Bakhtari, from ‘Ammar, who said: "If they were to strike us until they reached the palm branches of Hajar, we would know that we are upon the truth and that they are upon falsehood."