Musnad Abu Ya'la al-Mawsili 42:200

Abu Khaythama narrated to us, Jarir narrated to us, from al-A'mash, from Abu Salih, from Abu Sa'id, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Noah will be called on the Day of Resurrection, and he will say: 'At Your service and ready to obey, O Lord.' He will say: 'Have you conveyed [the message]?' He will say: 'Yes, O Lord.' He will say to his nation: 'Did he convey [the message] to you?' They will say: 'No warner came to us.' It will be said: 'Who will testify for you?' He will say: 'Muhammad (may Allah bless him and grant him peace) and his nation.' He said: 'So they will testify that he had indeed conveyed [the message], and the Messenger will be a witness over you.' That is the meaning of His saying: 'Thus We have made you a median nation that you may be witnesses over the people' [Al-Baqarah: 143]." He said: "And the median (al-wasat) is the just (al-'adl)."