Musnad Ahmad 32:1265

'Abd al-Samad narrated to us, my father narrated to me, Abu al-Tayyah Yazid ibn Humayd al-Dab'i narrated to me, he said: Anas ibn Malik narrated to me, he said: When the Messenger of Allah (peace and blessings of Allah be upon him) arrived in Medina, he stayed in the upper part of Medina in a neighborhood called Banu 'Amr ibn 'Awf. He stayed among them for fourteen nights. Then he sent for the notables of Banu al-Najjar, and they came with their swords girded. He said: It is as if I am looking at the Messenger of Allah (peace and blessings of Allah be upon him) on his mount, with Abu Bakr behind him, and the notables of Banu al-Najjar around him, until he stopped at the courtyard of Abu Ayyub. He said: He used to pray wherever the prayer time overtook him, and he would pray in the sheepfolds. Then he ordered the mosque to be built, so he sent for the notables of Banu al-Najjar, and they came. He said: "O Banu al-Najjar, name a price for me for this garden of yours." They said: "No, by Allah, we do not seek its price from anyone except Allah." He said: And it contained what I am telling you; it contained the graves of the polytheists, it contained ruins, and it contained palm trees. The Messenger of Allah (peace and blessings of Allah be upon him) ordered the graves of the polytheists to be dug up, the ruins to be leveled, and the palm trees to be cut down. He said: They arranged the palm trunks toward the qibla of the mosque, and they made its doorposts of stone. He said: They began to carry those rocks while chanting rajaz poetry, and the Messenger of Allah (peace and blessings of Allah be upon him) was with them, saying: "O Allah, there is no good except the good of the Hereafter, so grant victory to the Ansar and the Muhajirun."