Musannaf Ibn Abi Shayba 2:1

Abu Abd al-Rahman Baqi ibn Makhlad narrated to us, he said: Abu Bakr ibn Abi Shayba narrated to us, he said: Waki’ narrated to us, he said: al-A’mash narrated to us, from ‘Amr ibn Murrah, from ‘Abd al-Rahman ibn Abi Layla, he said: The companions of the Messenger of Allah (may Allah bless him and grant him peace) narrated to us that ‘Abd Allah ibn Zayd al-Ansari came to the Prophet (may Allah bless him and grant him peace) and said: "O Messenger of Allah, I saw in a dream as if a man stood up, wearing two green garments, upon the trunk of a wall. He performed the Adhan in pairs, and he performed the Iqamah in pairs, and he sat for a sitting." He said: Bilal heard that, so he stood up and performed the Adhan in pairs, and he performed the Iqamah in pairs, and he sat for a sitting.