It is narrated from Hazrat Abu Saeed Khudri (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: On the Day of Resurrection, a prophet will come, and with him will be only one man; with another prophet, there will be only two men. They will be asked: Did you convey the message of Tawheed? They will reply: Yes! Then their people will be called and asked: Did he convey the message to you? They will reply: No. The prophet will be asked: Who will testify in your favor? He will reply: Muhammad (peace and blessings be upon him) and his Ummah. Then they will be asked: Did they convey the message of Tawheed to their people? They will reply: Yes! They will be asked: How did you know? They will reply: Our Prophet came to us and informed us that all the prophets had conveyed the message of Tawheed. This is the meaning of the verse "Thus We have made you a just (wasat) community," that in this, "wasat" means moderate.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 11558