The Prophet (sa) Said:
"On the Day of Resurrection, Noah will be brought and asked, 'Did you convey (the message)?' He will say, 'Yes, O Lord.' His nation will be asked, 'Was the message conveyed to you?' They will answer, 'No warner came to us.' He (the Lord) will say (to Noah), 'Who are your witnesses?' He will answer, 'Muhammad and his nation.' Then you (i.e., the followers of Muhammad) will be brought and will give witness." Then the Messenger of Allah (sallallaahu 'alaihi
wa sallam) read the verse,
"Thus have We made of you a nation justly balanced," -
he stated, "(That is)
just,"- "that you may be witnesses over the people and the Messenger a witness over yourselves."
[Bukhari]