Once, Abdur Rahman bin Zaid bin Khattab, while delivering a sermon regarding the Day of Doubt, said: I have sat in the gatherings of the companions of the Noble Prophet (peace be upon him) and I have asked them about this matter. They told me that the Noble Prophet (peace be upon him) said: Fast upon sighting the moon and celebrate Eid upon sighting the moon and perform sacrifice. And if there are clouds, then complete the count to thirty. And if two Muslims give testimony of sighting the moon, then begin fasting and celebrate Eid.