Hazrat Samurah bin Jundub (may Allah be pleased with him) once said during a sermon that the Messenger of Allah (peace and blessings be upon him) said: "Do not be deceived by Bilal's call to prayer or this whiteness until the true dawn appears. The true dawn is the light that spreads across the horizon in width."
Hadith Referenceمسند احمد / أول مسند البصريين / 20203
Hadith Gradingحکم دارالسلام:صحيح الغيره، م: 1094، وهذا إسناد حسن